ProDeveloperTutorial – Selected Competitive Programming Questions for Interview

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Arrays Questions
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1. Arrays: Given an array of integers in ascending order, return index of the two numbers such that they add up to a specific key provided. 
2. Arrays: Sort an array of 0s, 1s and 2s in C 
3. Arrays: Given an array, the difference between the elements is one, find if the “key” element is present or not. 
4. Arrays: Given an unsorted array, find the minimum difference between 2 elements. 
5. Arrays: Given an unsorted array, find the least difference between the element pairs. Display all the pairs present. 
6. Arrays: Given an unsorted array, and a key. Find 2 elements such that the difference between the elements is equal to the key. 
7. Arrays: Given an unsorted integer array, find the smallest missing positive integer. 
8. Arrays: Given an array, find all the repeated elements in C language.
9. Arrays: Given an integer value, convert it into roman number.
10. Arrays: Given a string, and number of rows, write the string in zigzag pattern. 
11. Arrays: Find the Container with Most Water explanation with diagram and solution 
12. Arrays: Implement next permutation, which rearranges numbers into the lexicographically next greater permutation of numbers.
13. Arrays: Given a collection of candidate numbers and a key, find all unique combinations in candidates where the candidate numbers sums to target.
14. Arrays: Given a collection of numbers that might contain duplicates, return all possible unique permutations in C++
15. Arrays: Merge Intervals in C++
16. Arrays: Jump Game II in CPP
17. Arrays: Sort Colors In Place
18. Arrays: Given two integers n and k, return all possible combinations of k numbers out of 1 … n.
19. Arrays: Given a set of distinct integers, nums, return all possible subsets (the power set).
20. Arrays: Given a sorted array nums, remove the duplicates in-place such that duplicates appeared at most twice and return the new length.
21. Arrays: Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand.
22. Arrays: Insert Interval
23. Arrays: Given a triangle, find the minimum path sum from top to bottom.
24. Arrays: Best time to buy sell stock
25. Arrays: Given a non-empty array of integers, every element appears twice except for one. Find that single one.
26. Arrays: Find the minimum element from an array that is sorted and is rotated, solution in C++
27. Arrays: Given an array, find the majority element, solution in C++
28. Arrays: Given the heights of histogram using an array, you need to find the largest area rectangle in that histogram. Solution in C++
29. Arrays: You are given an unsorted array, and a key number, find the largest number of that key position.
30. Arrays: Given an array, that has zero. Move all the zero at the end, but maintain the relative order of other elements.
31. Arrays: Find the k’th smallest/largest element in an array
32. Arrays: Move all the negative number in beginning
33. Arrays: Given an array, rotate it one time
34. Arrays: Merge Two Sorted arrays without using extra space
35. Arrays: Find common element in 3 sorted arrays.
36. Arrays: Rearrange the array with one positive and one negative number.
37. Arrays: Find a triplet that sum to a given value
38. Arrays: Find the median of 2 sorted arrays of same size
39. Arrays: Merge sorted array inplace
40. Arrays: Find triplet with minimum sum
41. Arrays: Program to check if an Array is Palindrome or not
42. Arrays: Check if 3 consecutive odds exist
43. Arrays: Check If N and Its Double Exist
44. Arrays: Find unique numbers that sum upto zero
45. Arrays: Find numbers with even number of digits
46. Arrays: Product of array except itself
47. Arrays: Cell state after K days
48. Arrays: Find the minimum number to an array so the sum becomes even
49. Arrays: Given an array and a number n, rotate the array by n steps to its right.
50. Arrays: Print in a Circular Array
51. Arrays: Find the closest greater element for every array element from another array
52. Arrays: Given an array, find minimum number of swaps required to sort the array
53. Arrays: Implement prefix sum array

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Strings Questions
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1. Strings: Group Anagrams in C++
2. Strings: Wildcard Matching
3. Strings: Simplify Path CPP
4. Strings: Given a 2D board and a word, find if the word exists in the grid.
5. Strings: check if the given string is valid or not explanation with solution
6. Strings: Decode Ways
7. Strings: Restore IP Addresses
8. Strings: Word Ladder
9. Strings: Given a string s, partition s such that every substring of the partition is a palindrome.
10. Strings: Given a sentence and maxWidth. Arrange the text in such a way that each line has exactly maxWidth characters and is fully justified.
11. Strings: You are given a sentence, reverse the string word by word
12. Strings: Given 2 strings, check if they are isomorphic strings.
13. Strings: You are given a string that contain a basic expression, calculate the result. Solution in C++.
14. Strings: Reverse a string
15. Strings: Print all the duplicates in a string
16. Strings: Program to check if strings are rotations of each other or not
17. Strings: Longest Repeating Subsequence
18. Strings: Given a string, print all the subsequence
19. Strings: Permutations of a given string
20. Strings: Divide binary string into sub strings with equal number of 0s and 1s.
21. Strings: Check balanced parenthesis
22. Strings: Word Break Problem
23. Strings: Convert a string into its mobile numeric keypad
24. Strings: Get the minimum number of inversions needed to make an expression balanced
25. Strings: Count the number of string in 2D character array
26. Strings: Convert Roman Numerals to Decimal
27. Strings: Longest Common Prefix
28. Strings: Minimum number of flips to make binary string alternate
29. Strings: Find the first repeated word in a string
30. Strings: Minimum swaps required for bracket balancing
31. Strings: Find the longest common subsequence between two strings.
32. Strings: Check if it is possible to re-arrange characters in a string, such a way that no two adjacent are same
33. Strings: Minimum characters to be added at beginning to make string palindrome
34. Strings: Remove all consecutive duplicates from the string
35. Strings: Find minimum operations required to transform a string into another string
36. Strings: Recursively print all sentences that can be formed from list of word lists
37. Strings: Remove all consecutive duplicates from the string
38. Strings: Given a string convert into its equivalent ASCII form
39. Strings: Second most repeated word in a sequence
40. Strings: Convert Postfix to Infix
41. Strings: Longest Prefix Suffix
42. Strings: Calculate the basic arithmetic expression as string
43. Strings: Calculate an expression with * and /
44. Strings: Given an encoded string, decode string
45. Strings: Number of Different Integers in a String
46. Strings: Longest Substring Of All Vowels in Order
47. Strings: Minimum Number of Swaps to Make the Binary String Alternating
48. Strings: Longer Contiguous Segments of Ones than Zeros
49. Strings: Check if Word Equals Summation of Two Words

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BitMagic Questions
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1. Bitwise Operators: Given two integers dividend and divisor, divide two integers without using multiplication, division and mod operator.
2. Bitwise Operators: The gray code is a binary numeral system where two successive values differ in only one bit.
3. Bitwise Operators: Reverse Bits
4. Bitwise Operators: Count the number of set bits
5. Bitwise Operators: Power of 2
6. Bitwise Operators: Missing Number
7. Bitwise Operators: Counting set bits in a number
8. Bitwise Operators: Hamming Distance
9. Bitwise Operators: Bitwise and of number range
10. Bitwise Operators: Find the two non repeating numbers.
11. Bitwise Operators: Count number of bits to be flipped to convert A to B
12. Bitwise Operators: Bitwise Set bit questions
13. Bitwise Operators: Copy set bits in a range
14. Bitwise Operators: Power Set
15. Bitwise Operators: Given a binary number, return the 1’s and 2’s complement of that number
16. Bitwise Operators: Add and subtract 2 numbers using bitwise operators.
17. Bitwise Operators: Calculate the square of a number and also check if that number is even or odd using bitwise operator.
18. Bitwise Operators: Check if the number has bits in alternate pattern and also check if the same number has equal number of set and unset bits using bitwise operators
19. Bitwise Operators: Given 2 numbers check if one number is complement of another and also check if those two numbers are same using bitwise operators
20. Bitwise Operators: Perform below operations using Bitwise Operators
21. Bitwise Operators: Perform below swapping operations using Bitwise operators
22. Bitwise Operators: Add 1 to a given number
23. Bitwise Operators: Toggle all even bits of a number
24. Bitwise Operators: Given a number “n”, calculate xor of 1 to n
25. Bitwise Operators: Given a binary string, check the divisibility of the string by 2^k
26. Bitwise Operators: Check if the given number is sparse or not
27. Bitwise Operators: Given a number, check if all the bits of the number are set
28. Bitwise Operators: Given a number, check if it has 2 adjacent set bits
29. Bitwise Operators: Bitwise AND of all even number from 1 to N
30. Bitwise Operators: Given a number, check if it is divisible by 8
31. Bitwise Operators: Bitwise Operations Tricks

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Linked List Questions
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1. Linked List: Given two non empty Linked List with non negative numbers, and numbers are stored in reverse order having single digit. Add the two list and return the result as a linked list. 
2. Linked List: Swap Nodes in Pairs solution in C
3. Linked List: Merge k sorted linked lists and return it as one sorted list in C++
4. Linked List: Reverse Linked List iterative and recursive in C++
5. Linked List: Intersection of Two Linked Lists in c++
6. Linked List: Rotate linked list by k nodes
7. Linked List: Remove Duplicates from Sorted List solution in CPP
8. Linked List: Reverse a linked list from position m to n. Do it in one-pass.
9. Linked List: Given a linked list, determine if it has a cycle in it.
10. Linked List: Sort a linked list using insertion sort.
11. Linked List: Given a linked list, check if it is a palindrome or not. Solution in C++
12. Linked List: Reverse Linked List in groups
13. Linked List: Move last element to front of a given Linked List
14. Linked List: Add 1 to the linked list
15. Linked List: Find middle element in Linked List
16. Linked List: Split circular Linked List into two halves
17. Linked List: Program to Check if a Singly Linked List is Palindrome
18. Linked List: Deletion from a Circular Linked List
19. Linked List: Reverse a Doubly Linked List
20. Linked List: Find pairs with a given sum in a DLL.
21. Linked List: Count triplets in a sorted DLL whose sum is equal to given value “k”.
22. Linked List: Sort a “k”sorted Doubly Linked list
23. Linked List: Rotate Doubly linked list by N nodes
24. Linked List: Flatten a Linked List
25. Linked List: Multiply two numbers represented by Linked Lists
26. Linked List: Delete nodes which have a greater value on right side using recursion
27. Linked List: Odd Even Linked List
28. Linked List: Perform binary search on a singly linked list
29. Linked List: Perform bubble sort on singly linked list
30. Linked List: Perform below operations on Circular Singly Linked List:
31. Linked List: Perform below delete operations from single linked list.
32. Linked List: Perform below delete operations from single linked list.
33. Linked List: Perform below operations from a circular linked list
34. Linked List: Given a linked list convert into peak list
35. Linked List: Perform bubble sort on Double linked list
36. Linked List: Check if a doubly linked list of characters is palindrome or not
37. Linked List: Perform the below delete operations on a Doubly Linked List
38. Linked List: Sort a nearly sorted doubly linked list
39. Linked List: Split a circular linked list into two halves
40. Linked List: Copy a linked list with given next and random pointer
41. Linked List: Given 2 linked list by choosing max element at each position
42. Linked List: Given a binary tree, convert into circular doubly linked list
43. Linked List: Convert a single linked list to circular linked list
44. Linked List: Count the number of rotations in sorted and rotated linked list
45. Linked List: Sort a linked list of 0, 1, 2
46. Linked List: Given a circular linked list, exchange first and last node
47. Linked List: Find 3 nodes whose sum equal to a given number
48. Linked List: Given a LL, find the kth node from middle towards the head
49. Linked List: Given 2 LL, find the first common element
50. Linked List: Insert node into the middle of the linked list
51. Linked List: Given Linked list and a value K, partition the list

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Stack Questions
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1. Stack: Given an expression in reverse polish notation, evaluate it and get the output in C++
2. Stack: Delete the middle element from the stack.
3. Stack: Check for balanced brackets using stack
4. Stack: Next Greater Element
5. Stack: Evaluate postfix expression
6. Stack: Insert at the end of stack
7. Stack: Reverse a stack using recursion
8. Stack: Sort a stack
9. Stack: Largest Rectangular Area in a Histogram
10. Stack: Length of the longest valid substring
11. Stack: Expression contains redundant bracket or not
12. Stack: Reverse the first “K” elements of a queue
13. Stack: Next Smaller Element
14. Stack: Remove All Adjacent Duplicates In String
15. Stack: Build an Array With Stack Operations
16. Stack: Make digit minimum by removing k digits.
17. Stacks: Minimum Insertions to Balance a Parentheses String
18. Stacks: Check if the given pattern exist in the array
19. Stack: Score of Parentheses
20. Stacks: Validate stack operations
21. Stack: Convert Infix to Postfix Expression
22. Stack: Postfix and prefix conversion
23. Stack: Prefix to infix conversion
24. Stack: Prefix to postfix conversion
25. Stack: Nearest smaller numbers on left side in an array
26. Stack: Given an array, you need to find the previous greater element
27. Stack: Print Bracket Number
28. Stack: Reversing the first K elements of a Queue
29. Stack: Check if stack elements are pairwise consecutive
30. Stack: Check if the expression contains redundant bracket or not
31. Stack: Check if an array is stack sortable
32. Stack: Check if valid parentheses in an expression
33. Stack: Given a string expression, check if it is balanced expression
34. Stack: Stock Span Problem
35. Stack: Delete consecutive same words in a sequence
36. Stack: Given an expression, get the minimum bracket reversal to make the expression balanced

 

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Searching and Sorting Questions
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1. Searching and Sorting: Maximum and minimum of an array using minimum number of comparisons
2. Searching and Sorting: Search an array where adjacent differ by at most k
3. Searching and Sorting: Count all distinct pairs with difference equal to k
4. Searching and Sorting: Maximum sum such that no two elements are adjacent
5. Searching and Sorting: Merge 2 sorted arrays
6. Searching and Sorting: print all subarrays with 0 sum
7. Searching and Sorting: Product of array except itself.
8. Searching and Sorting: Minimum number of swaps required to sort an array
9. Searching and Sorting: K-th Element of Two Sorted Arrays
10. Searching and Sorting: Find the missing number in Arithmetic Progression
11. Searching and Sorting: Find the majority element in the array
12. Searching: Find all the triplets with zero sum
13. Searching: Check if all occurrence if a character appear together
14. Searching: Check if there exist 2 elements in an array whose sum is equal to the sum of rest of the array
15. Searching: Count the number of 1s in a sorted binary array
16. Searching: Count number of occurrence in a sorted array
17. Searching: Find median of two sorted array of different sizes
18. Searching: Allocate minimum pages
19. Searching: Find fixed point in the given array
20. Searching: Given an number, find the numbers whose factorials end with n zeros
21. Searching: Find the closest number in the sorted array
22. Searching: Given a string and a key, find the smallest letter that is greater than the key
23. Searching: Given an sorted rotated array, find the given key is present
24. Searching: Find index of an extra element in a sorted array
25. Searching: Given an array, find the largest pair sum
26. Searching: Find the k maximum elements of an array in original array.
27. Searching: Aggressive Cows
28. Searching: Find the missing elements of 2 sorted arrays
29. Searching: Find the missing number

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Sorting Questions
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1. Sorting: Given an array, sort the elements alternatively
2. Sorting: Get union of 2 sorted arrays
3. Sorting: Given an array, return the number of steps required to make array elements same
4. Sorting: Given an array, count inversions
5. Sorting: Given 2 arrays, return minimum number of platforms required for a railway station
6. Sorting: Minimum increment to make array unique
7. Sorting: Merge 2 sorted arrays
8. Sorting: Check if any interval completely overlaps other
9. Sorting: Given an array, you need to check if it has contiguous integers
10. Sorting: Given an array, minimize sum of product of consecutive pairs
11. Sorting: Check if reversing sub array make the array sorted
12. Sorting: Check if two arrays are equal or not
13. Sorting: Check if the array is Arithmetic Progression
14. Sorting: Check if a given array is K sorted or not
15. Sorting: Check if the array can be fit into another array by re-arranging the elements.
16. Sorting: Given an unsorted array and a value x, you need to check if a pair exist for given difference
17. Sorting: Merge two sorted arrays without extra space.
18. Sorting: Given a string, sort it by frequency of characters
19. Sorting: Get the intersection of 2 arrays
20. Sorting: Sort an array having partially sorted and partially unsorted array
21. Sorting: Given an array, you need to remove the elements to make the array as sorted.
22. Sorting: Find minimum difference between any two elements in a array
23. Sorting: Print elements occurred only once in the array
24. Sorting: Find the missing element of a range in an array
25. Sorting: Find a pair with maximum product in array of integers

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Binary Searching Questions
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1. Binary Search: Given an array sorted in ascending order and is rotated at some pivot, given a target value to search, if found in the array return its index
2. Binary Search: Search a 2D Matrix in C++
3. Binary Search: Binary search on an array that is in descending order
4. Binary Search: Order-Agnostic Binary Search
5. Binary Search: Find the first and last occurrence of an element
6. Binary Search: Find the number of times a Sorted array is Rotated
7. Binary Search: Searching in a Nearly Sorted Array
8. Binary Search: Find Floor of an element in a Sorted Array
9. Binary Search: Find Ceil of an element in a Sorted Array
10. Binary Search: Find position of an element in an Infinite Sorted Array
11. Binary Search: Find the index of first 1 in an infinite sorted array of 0s and 1s
12. Binary Search: Peak Element
13. Binary Search: Find maximum element in Bitonic Array
14. Binary Search: Search An Element in Bitonic Array
15. Binary Search: Get the rotation count in sorted rotated array
16. Binary Search: Count the number of 1’s in an array sorted in decreasing order.
17. Binary Search: Searching and Sorting: Get the fixed point in an array

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Queue Questions
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1. Queue: Given a Linked list, construct a complete binary tree
2. Queue: Sort a queue without using extra space
3. Queue: Reverse first K elements in the queue
4. Queue: Implement priority queue using Linked List
5. Queue: Find the first non repeating character in the stream
6. Queue: Given a queue, reverse it
7. Queue: Given a queue and element k, revert the first k element of the queue
8. Queue: Implement dequeue using doubly linked list
9. Queue: Implement queue using stacks
10. Queue: Given a queue, interleave first half of the queue with second half
11. Queue: Given a queue, check if queue can be sorted using stack
12. Queue: Given 2 sorted arrays, you need to merge them using priority queue
13. Queue: Reverse a stack using queue
14. Queue: Maximum of all subarrays of size K

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Matrix Matrix Questions
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1. Matrix: You are given an n x n 2D matrix rotate it by 90 degrees (clockwise) in C++.
2. Matrix: Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order.
3. Matrix: Given a positive integer n, generate a square matrix filled with elements from 1 to n2 in spiral order in C++
4. Matrix: Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in-place.
5. Matrix: Search a 2D Matrix in C++
6. Matrix: Check if the given board is valid Sudoku or not explanation with solution in CPP
7. Matrix: Surrounded Regions
8. Matrix: Soduku Solver
9. Matrix: Given a 2d matrix, filled with 1 and 0. Find the maximum sub-matrix that has only 1’s and return the area.
10. Matrix: Find median in a row wise sorted matrix.
11. Matrix: Kth smallest element in a sorted matrix
12. Matrix: Get the common elements in all row of a matrix.
13. Matrix: Given a matrix, print the boundary elements
14. Matrix: Given a matrix, rotate matrix 180 degree
15. Matrix: Given a matrix, you need to find the sum of diagonals of a matrix.
16. Matrix: Given a matrix, find the transpose of the matrix
17. Matrix: Given a matrix, check if the matrix is sparse or not
18. Matrix: Given a matrix, check if it is orthogonal or not
19. Matrix: Find common elements in all rows of a given matrix
20. Matrix: Given a matrix, count the number of sorted rows
21. Matrix: Given a matrix, count the majority element
22. Matrix: Given a binary matrix, find the rows with max 1s
23. Matrix: Given a matrix, you need to count the number of rows and columns whose sum equal to diagonal sum
24. Matrix: Given a matrix, count zero in row wise and column wise matrix
25. Matrix: Given a 2D matrix, find the peak element.
26. Matrix: Given a matrix, set it to zero

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Recursion Questions
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1. Recursion: Count the number of ways a baby can reach the n’th stair taking 1 or 2 steps at a time in C language. 
2. Recursion: Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses. 
3. Recursion: Given a collection of distinct integers, return all possible permutations.
4. Recursion: Implement pow(x, n), which calculates x raised to the power n (xn) in C++
5. Recursion: Count the ways to decode a digit sequence
6. Recursion: Get the nth Fibonacci Number
7. Recursion: Get the least number of perfect squares
8. Recursion: Convert a given decimal number into binary using recursion
9. Recursion: Reverse the queue using recursion
10. Recursion: Given two numbers, add them recursively
11. Recursion: Power of three
12. Recursion: Check if a number is palindrome using recursion
13. Recursion: Print N to 1 using recursion
14. Recursion: Print alternate node in a Linked List using recursion
15. Recursion: Given a string and a sub-string, count the number of occurrence recursively.
16. Recursion: Given a number, count the number of ways to express a number as sum of powers.
17. Recursion: Given a decimal number, convert into binary number using recursion
18. Recursion: Given a stack, delete the middle element using recursion
19. Recursion: You are given a stack, reverse it using recursion
20. Recursion: Given a linked list, find the middle element recursively
21. Recursion: Given a number, generate all binary strings.
22. Recursion: Given a string, find the occurrence of first uppercase letter in the string.
23. Recursion: Remove adjacent duplicates in the string.
24. Recursion: Given an array, generate all sub arrays using recursion
25. Recursion: Remove K adjacent duplicate in a string
26. Recursion: Handshake problem

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Heaps Questions
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1. Heaps Introduction
2. Heap: Heap Sort
3. Heap: Max Heap and Min heap using Priority Queue
4. Heaps: Build Min Heap from an Array
5. Heaps: Sort an Array using heap
6. Heaps: Find kth smallest in an unsorted array
7. Heaps: Merge “K” sorted arrays
8. Heap: Kth smallest element.
9. Heap: Return k largest element
10. Heap: Sort a K sorted array or nearly sorted array
11. Heap: K closest number
12. Heap: Top K Frequent Elements
13. Heap: Top K Frequent Words
14. Heap: Sum of all the elements between k1 and k2 smallest elements
15. Heap: kth largest element in a stream
16. Heap: Given two max heaps, merge them
17. Heap: Find median in a stream
18. Heap: Check if given a binary tree is a Heap
19. Heap: k closest number
20. Heap: Convert Min Heap to Max Heap
21. Heap: Given an array, sort the array using min heap
22. Heap: Given an array, check if the array represents Binary Max Heap
23. Heap: kth largest in a stream
24. Heap: K Closest Points To Origin
25. Heap: Find the minimum product of k integers in an array
26. Heap: Given an array, find the kth largest element in the array
27. Heap: Given an array, find the top K frequency elements
28. Heap: Given an array, find the kth smallest pair sum

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Hashing Questions
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1. Hashing: Given an array of integers in ascending order, return index of the two numbers such that they add up to a specific key provided. 
2. Hashing: You are given an array, you need to return kth distinct element
3. Hashing: Longest consecutive sequence
4. Hashing: Given an array, check if the array is a permutation of numbers from 1 to N.
5. Hashing: Given a array, you need to find a duplicate within k distance in the array.
6. Hashing: Given a string, check if it is isogram or not
7. Hashing: Given an array, find two non overlapping pairs having equal sum
8. Hashing: Given 2 strings, find uncommon characters
9. Hashing: Replace all the elements of the array by its rank in the array
10. Hashing: Given a sorted array, count the absolute distinct count
11. Hashing: Given 2 arrays, check if they are equal or not
12. Hashing: Given two arrays, sort first array according to the order of second array
13. Hashing: Find the first repeating element and index in the array
14. Hashing: Given an array, find the first missing positive number
15. Hashing: Given an array, find the majority element
16. Hashing: Given an array, find the element that occurs odd number of times
17. Hashing: Given 2 arrays, and a value x, you need to find the pairs sum equal to the given value of x.
18. Hashing: Given an array and a value k, return top k frequent elements
19. Hashing: Given an array, you need to find the missing number
20. Hashing: Given an array, count all the subsets with even numbers and are distinct
21. Hashing: Given an array, you need to count the frequency if the array elements

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Dynamic Programming Questions
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1. Dynamic Programming: Longest Palindromic Substring In C++ 
2. Dynamic Programming: Given an input string (s) and a pattern (p), implement regular expression matching with support for ‘.’ and ‘*’. 
3. Dynamic Programming: Rain water trapping
4. Dynamic Programming: Unique Paths Solution in CPP
5. Dynamic Programming: Unique Paths 2
6. Dynamic Programming: Minimum Path Sum in CPP
7. Dynamic Programming: Longest Increasing Subsequence
8. Dynamic Programming: Longest Bitonic Subsequence
9. Dynamic Programming: Get Max Coin In Game problem.
10. Dynamic Programming: Rod Cutting Problem
11. Dynamic Programming: Box Stacking Problem
12. Dynamic Programming: Building Bridges
13. Dynamic Programming: Egg Dropping Problem
14. Dynamic Programming: Min Edit Distance
15. Dynamic Programming: 0 1 Knapsack Problem using Dynamic Programming
16. Dynamic Programming: Binomial Coefficiet Problem
17. Dynamic Programming: Permutation Coefficient
18. Dynamic Programming: Get the nth catalan number
19. Dynamic Programming: Subset sum problem
20. Dynamic Programming: Unbounded Knapsack Problem
21. Dynamic Programming: Equal Sum partition
22. Dynamic Programming: Climb the stairs with minimum cost
23. Dynamic Programming: Robbing Houses
24. Dynamic Programming: Get the sum by deleting elements from the array
25. Dynamic Programming: Count of subset sum with a given sum
26. Dynamic Programming: Minimum subset difference
27. Dynamic Programming: Target Sum
28. Dynamic Programming: Count the number of subset with a given difference
29. Dynamic Programming: Minimum Number of swaps to make array increasing
30. Dynamic Programming: Longest Common Subsequence
31. Dynamic Programming: Print Longest Common Sub-sequence
32. Dynamic Programming: Length of Shortest Common Supersequence
33. Dynamic Programming: Print Shortest Common Supersequence
34. Dynamic Programming: Minimum number of deletions and insertions to convert one string into another
35. Dynamic Programming: Longest repeating subsequence
36. Dynamic Programming: Check if one string is a subsequence of another
37. Dynamic Programming: Count how many times string 1 appears as substring in string 2.
38. Dynamic Programming: Longest Common Substring
39. Dynamic Programming: Get the count of delete operations on 2 strings.
40. Dynamic Programming: Find the Maximum and minimum of an array

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Divide and conquer Questions
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1. Divide and Conquer: Implement pow(x, n), which calculates x raised to the power n (xn) in C++

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Backtracking Questions
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1. Backtracking: Given an array of non repeating numbers and a key, find all the unique combinations in that array, where the sum of those combination is equal to the key.
2. Backtracking: Letter Combinations of a Phone Number
3. Backtracking: The n-queens puzzle is the problem of placing n queens on an n×n chessboard such that no two queens attack each other.
4. Backtracking: Subsets II in CPP
5. Backtracking: Partition string into its palindrome
6. Backtracking: You are given an array with repeated elements and a key element, find all unique combination to the key
7. Backtracking: Get the k combination from an array of 1 to n
8. Backtracking: Find combination sum of k numbers that sum up to n
9. Backtracking: Letter case permutation
10. Backtracking: Get the sequential digits from the given range
11. Backtracking: Return the number of queens possible in a chessboard
12. Backtracking: Partition to K Equal Sum Subsets
13. Backtracking: Get maximum sum in a matrix

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Binary Trees Questions
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1. Binary Trees: Get difference between values at Even and Odd level in a binary tree
2. Binary Tree: Get Number of Nodes in a Binary Tree
3. Binary Tree: Display nodes at given level in Binary Tree
4. Binary Tree: Display Reverse Level Order Traversal by using queue
5. Binary Tree: Perform PreOrder traversal on a Binary Tree by without Recursion
6. Binary Tree: Perform InOrder traversal on a Binary Tree by without Recursion
7. Binary Tree: Perform PostOrder traversal on a Binary Tree by without Recursion
8. Binary Tree: Convert a binary tree to its Mirror Tree
9. Binary Tree: Delete a binary tree
10. Binary Tree: Get Level of a Given Node
11. Binary Tree: Display elements between any two given level
12. Binary Tree: Check if binary tree is a height balanced tree?
13. Binary Tree: Find Parent of a given node value in Binary Tree
14. Binary Tree: Find Sibling node of a given node value in Binary Tree
15. Binary Tree: Get Sum of all nodes formed from Root to Leaf Path
16. Binary Tree: Get Sum of all Leaf Nodes in Binary Tree
17. Binary Tree: Find Maximum or Minimum in Binary Tree
18. Binary Tree: Check if Binary Tree is Foldable Tree
19. Binary Tree: Check if two Binary Trees are Isomorphic
20. Binary Tree: Display all the leaf nodes from left to right and right to left in a tree
21. Binary Tree: Get count Non-Leaf nodes in a Binary Tree
22. Binary Tree: Get the count full nodes in a Binary
23. Binary Tree: Bottom view of binary Tree
24. Binary Tree: Boundary Traversal of Binary Tree
25. Binary Tree: Top view of a binary tree
26. Binary Tree: Left view and right view of a Binary Tree
27. Binary Tree: Level Order Traversal
28. Binary Tree: Vertical Order Traversal
29. Binary Tree: Height or Max depth if a BTree
30. Binary Tree: Spiral order or Zigzag traversal of a Binary Tree
31. Binary Tree: Diameter of a Binary Tree
32. Binary Tree: Lowest Common ancestor of a Binary Tree.
33. Binary Tree: Check if 2 nodes are mirror of each other
34. Binary Tree: Add all the node values in a Binary Tree or Sum of a Binary tree
35. Binary Tree: Print the number of leaf nodes in a binary tree
36. Binary Tree: Print all the paths from root node to leaf node
37. Binary Trees: Diagonal Traversal of a Binary tree
38. Binary Trees: Kth Ancestor of a Tree Node
39. Binary Tree: Given a binary tree, check if the tree is perfect or not.
40. Binary Tree: Maximum path sum in a binary tree
41. Binary Tree: Convert BST to Min Heap
42. Binary Tree: You are given a binary tree, you need to print the extreme nodes in alternate order.
43. Binary Tree: Given a binary tree, find the maximum path sum between two leaves
44. Binary Tree: Given a binary tree and a target, delete leaf nodes having value target
45. Binary Tree: Given a binary tree and a target, burn it
46. Binary Tree: Given a binary tree, check if the tree is a children sum property
47. Binary Tree: Given a binary tree, check if there is duplicate subtree and return the duplicate subtree
48. Binary Tree: Given two trees, check if the tree is subtree of another tree
49. Binary Tree: Given a binary tree and two nodes, check if they are cousins
50. Binary Tree: Given a binary tree, invert it

 

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Graph Questions
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1. Graph: Detect a cycle in a directed graph
2. Graph: Detect a cycle in a undirected graph
3. Graph: Check if the given edge is a bridge in the graph
4. Graph: Check if undirected graph is connected or not
5. Graph: Count the number of connected components in an undirected graph
6. Graph: Reverse a directed graph
7. Graph: Given an directed graph, find the in and out degree of all vertices
8. Graph: Find there is a path between 2 nodes in a directed graph
9. Graph: Get the unique lengths of connected components of an undirected graph.
10. Graph: Find if there is a path between 2 nodes in an undirected graph
11. Graph: Check if a graph is a strongly connected using Kosaraju DFS algorithm
12. Graph: Dice Sum Problem
13. Graph: DFS graph traversal
14. Graph: Find the number of Islands
15. Graph: Check if the given courses can be completed with prerequisites
16. Graph: Given a graph, check if it is bipartite or not – Using BSF
17. Graph: Given a graph with source and destination, count all the possible path between two vertices
18. Graph: Given a matrix, find the distance of nearest cell having 0
19. Graph: Flood Fill algorithm
20. Graph: Find minimum time to rot all the oranges
21. Graph: Get all the paths from source to destination
22. Graph: Given a matrix, replace ‘o’ with ‘x’, if surrounded by ‘x’
23. Graph: You are given a graph, clone the graph using deep copy
24. Graph: Given a dictionary and a matrix, find all the words from the dictionary found in matrix
25. Graph: Given a binary matrix, find the largest region of 1
26. Graph: Given a matrix, find the number of closed islands

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Binary Search Trees Questions
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1. Binary Search Trees: Deletion of a node in a BST
2. Binary Search Trees: Find min and max value in a BST
3. Binary Search Trees: Find the Inorder predecessor and successor for a given key in BST
4. Binary Search Trees: A program to check if a binary tree is BST or not
5. Binary Search Trees: Convert a BST into greater sum tree
6. Binary Search Trees: LCA in a BST
7. Binary Search Trees: Construct BST from preorder traversal
8. Binary Search Trees: Convert Binary Tree into Binary Search Tree.
9. Binary Search Trees: Convert a normal BST into a Balanced BST
10. Binary Search Trees: Merge Two balanced BST
11. Binary Search Trees: Kth Largest Element in a BST
12. Binary Search Trees: Count the number of BST nodes that lie in a given range.
13. Binary Search Trees: Find triplet sum in BST
14. Binary Search Trees: Check if the pre-order is a valid BST
15. Binary Search Trees: Check if the BST has a dead end
16. Binary Search Trees: Correct a BST where 2 nodes are swapped
17. Binary Search Tree: Unique Binary Search Trees
18. Binary Search Trees: Check If Preorder Traversal Is Valid BST
19. Binary Search Trees: Given an array, check if it represents inorder traversal of BST.
20. Binary Search Trees: Given a BST, check if each internal node has only one child
21. Binary Search Trees: Given a BST and a key, find the next smaller element of that key
22. Binary Search Trees: Given a BST and a range, return the range sum of that BST
23. Binary Search Trees: Given a BST, find median in BST
24. Binary Search Trees: Given 2 BST, check if both contain same set of elements
25. Binary Search Trees: Given a sorted array, convert into balanced bst
26. Binary Search Trees: Given 2 BST, print common nodes in the BST

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Greedy Questions
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1. Greedy: Add elements in an array so the sum is equal to the given range
2. Greedy: Remove k digits from a number to make it a smallest integer.
3. Greedy: Get the minimum platforms needed to avoid delay in the train arrival.
4. Greedy: Check if the string is a substring of another string
5. Greedy: Remove overlapping intervals.
6. Greedy: Maximum meetings in one room
7. Greedy: Distribute Candy
8. Greedy: Schedule task efficiently
9. Greedy: Shuffle array so that one array element is greater than other array element
10. Greedy: Maximum sum of absolute difference of an array
11. Greedy: Juice change
12. Greedy: Perform operations on a broker calculator
13. Greedy: Remove covered intervals.
14. Greedy: String break problem
15. Greedy: Connect ropes with minimum cost.
16. Greedy: Assign maximum cookies
17. Greedy: Non overlapping intervals
18. Greedy: Minimum swaps to make strings equal
19. Greedy: Insert new interval
20. Greedy: Reorganize String
21. Greedy: Check for Increasing triplet subsequence
22. Greedy: Given a string, partition the string such that each letter appears at only one part
23. Greedy: Given an array, find the longest alternative subsequence
24. Greedy: Check if a given string becomes palindrome by deleting atmost one char
25. Greedy: Get the maximum number by swapping once
26. Greedy: Given a string, return the length of longest palindrome
27. Greedy: Given a string, check if it is a valid parenthesis or not

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2 pointers Questions
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1. Two Pointers: Given an array, find 3 elements such that [a + b + c] = 0. Find all the 3 unique elements. 
2. Two Pointers: Given an array of n integers and an integer “key”, find three integers in the array such that the sum is closest to key. 
3. Two Pointers: Given an array n integers and an integer key, are there four elements a, b, c, and d in the array such that a + b + c + d = key? Find all unique quadruplets in the array which gives the sum of key. 
4. Two Pointers: Rain water trapping
5. Two Pointers: Reverse an array
6. Two Pointers: Arrays: Given an array find the duplicate number
7. Two Pointers: Arrays: Minimum swaps required to bring all elements less than or equal to k together
8. Two Pointers: Arrays: Get minimum number of merge operations to make an array palindrome
9. Two Pointers: Given an array and a value “m”, choose “m” elements having minimum difference between max and min
10. Two Pointers : Move all negative numbers to beginning and positive to end using extra space
11. Two Pointers: Count pairs with sum less than target
12. Two Pointers: Meeting rooms
13. Two Pointers: Given a string with special characters, reverse only alphabets
14. Two Pointers: Minimum boats to save people
15. Two Pointers: Given an array, sort the array by making element squares
16. Two Pointers: Given 2 arrays, find the common elements
17. Two Pointers: Given a binary array, return maximum consecutive ones
18. Two Pointers: Given a string, reverse the string by preserving whitespace.
19. Two Pointers: Given a binary string, check if the string has most number of contiguous segment of one
20. Two Pointers: Given an array and a value k, return the count of pairs with k difference
21. Two Pointers: Given two arrays find the intersection of two arrays
22. Two Pointers: Given two arrays with duplicate, you need to return the union of two arrays
23. Two Pointers: Given an array and a value K, you need to return the size of minimum subarray that is equal to k
24. Two Pointers: Given a array and a value k, return the number of subarray whose product is less that k
25. Two Pointers: Celebrity Problem
26. Two Pointers: Given an array, return the count of smallest subarray to be removed to make the remaining array sorted

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Sliding Window Questions
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1. Sliding Window: Strings: Smallest distinct window
2. Sliding Window: Strings: Minimum Window Substring
3. Sliding Window: Given a string, get the number of substrings having ‘a’, ‘b’, ‘c’
4. Sliding Window: Given an array and integer k, find the max sum of distinct subarray of length k
5. Sliding Window: Given an array and size k, find the first negative integer in each window of size k
6. Sliding Window: Given an array and a value k, find the maximum average subarray
7. Sliding Window: Return the maximum consecutive ones after flipping k zeros
8. Sliding Window: Return the number of sub array size k that is greater than or equal to threshold
9. Sliding Window: Given a string a variable k, count substring with k frequency characters
10. Sliding Window: Return he longest length of the substring with consecutive characters
11. Sliding Window: Maximum consecutive ones by flipping K bits
12. Sliding Window: Given an array, count maximum number of ones
13. Sliding Window: Subarrays with k odd numbers
14. Sliding Window: Longest substring without repeating character
15. Sliding Window: Longest substring after character replacement
16. Sliding Window: Return count of subarray with sum equal to k
17. Sliding Window: Given a string you need to find the longest non repeating substring
18. Sliding Window: Return length of longest subarray with having at most k frequency
19. Sliding Window: Fruits into baskets
20. Sliding Window: Maximum points you can obtain from cards
21. Sliding Window: Subarray with k different integers
22. Sliding Window: Smallest sum of contiguous subarray
23. Sliding Window: Given an array and a target value, get the subarray product less than k

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Merge interval pattern
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1. Merge interval pattern: Merge Overlapping Intervals
2. Merge interval pattern: Find intersection of all intervals
3. Merge interval pattern: Check if two intervals overlap
4. Merge interval pattern: Check if person can attend all the meetings
5. Merge interval pattern: Make Intervals Non Overlapping

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Prefix sum problems
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1. Prefix sum problems: Given an array find Equilibrium Index
2. Prefix sum problems: Bitwise OR of sum of all subsequence of the array
3. Prefix sum problems: Maximum equilibrium sum in an array
4. Prefix sum problems: Get original array from Prefix sum array
5. Prefix sum problems: Find the largest subarray with sum 0
6. Prefix sum problems: Longest subarray with sum k
7. Prefix sum problems: Given an array and value k, return the count of subarray with sum k
8. Prefix sum problems: Given bianry array and a value k, return the count of subarray sum

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Kadane’s Algorithm
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1. Kadane’s Algorithm: Maximum Subarray Sum
2. Kadane’s Algorithm: Maximum Circular Subarray Sum
3. Kadane’s Algorithm: Maximum Product Subarray
4. Kadane’s Algorithm: Maximum Subarray Sum after removing at most one element
5. Kadane’s Algorithm: Maximum Sum Rectangle In A 2D Matrix
6. Kadane’s Algorithm: Maximum Product Subarray
7. Kadane’s Algorithm: minimum size subarray sum
8. Kadane’s Algorithm: Largest sum increasing contiguous subarray
9. Kadane’s Algorithm: Maximum Product Subarray