Sliding Window: Given an array and size k, find the first negative integer in each window of size k

Problem Statement:

You are given an array and a integer K.

You need to find the first -ve integer for each window of size k.

return 0, if there are no 0ve integers.

Example:

Input: arr[] = [-1, 2, 3, -4, 5] k = 2

Output: [-1, 0, -4, -4] 

Explanation:  First negative integer for each window size of 2

[-1, 2] = -1
[2, 3] = 0
[3, -4] = -4
[-4, 5] = -4

Solution 1: Sliding window

We will use sliding window in this solution.

We will take a temp variable to check the first -ve integer of the current window and print it.

Then slide the window and update the results accordingly.

Time Complexity: O(1)
Space Complexity: O(1)

Code Solution

#include <iostream>
#include <vector>

using namespace std;


void solution(vector<int>& arr, int k)
{
	int n = arr.size();
	bool isNeg;

	for (int i = 0; i<(n-k+1); i++)
	{
	  isNeg = false;
	  for (int j = 0; j<k; j++)
	  {
	     if (arr[i+j] < 0)
	     {
	        cout<<arr[i+j]<<" ";
	        isNeg = true;
	        break;
	     }
	  }
	  if (!isNeg)
	     cout<<"0 ";
	}
}
int main() 
{
    vector<int> arr = {-1, 2, 3, -4, 5};  
    int k = 2;

    solution(arr, k);

    return 0;
}

Output

-1 0 -4 -4