Greedy: Remove k digits from an number to make it a smallest integer.
Problem Statement: You are given a number and integer k. You need to remove k digits from the number and it should return the smallest integer…
Greedy: Add elements in an array so the sum is equal to the given range
Problem Statement: You are given sorted array, and an integer K. You need to add elements in such a way that any number in the range [1, k]…
Greedy: Remove duplicates from a string
Problem Statement: You are given a string s, you need to remove duplicate letters so that every letter should appear only once. The result…
Binary Search Trees: Flatten BST to sorted list
Problem Statement: You are given a root of a binary tree. You need to flatten into a sorted list. Solution We need to do inorder traversal.…
Binary Search Trees: Correct a BST where 2 nodes are swapped
Problem Statement: You are given a root node of a binary search tree where 2 nodes are swapped. You need to correct the BST and return it.…
Binary Search Trees: Check if the BST has a dead end
Problem Statement: You are given a root node of a BST. You need to check if it has a dead end or not. A dead end is a node, where you will not…
Binary Search Trees: Check if the pre-order is a valid BST
Problem Statement: You are given an array of integers in pre-order fashion. Then you need to check if it is a valid BST. Solution pre-order…
Binary Search Trees: Find triplet sum in BST
Problem Statement: You are given a BST node and a key. YOu need to find if that key exist any triplet sum in given BST. Solution We do…
Binary Search Trees: Convert sorted DLL to Balanced BST
Problem Statement: You are given an DLL where the nodes are sorted in ascending order. we need to construct Balanced BST in-place. In-place…
Binary Search Trees: Count the number of BST nodes that lie in a given range.
Solution The solution is very simple. For every node visited, check if the node lies in range, if yes, then increment the count. Then…