SetMatrixZero.cpp

/*
Set Matrix Zeros
Given a matrix, A of size M x N of 0s and 1s. If an element is 0, set its entire row and column to 0. Note: This will be evaluated on the extra memory used. Try to minimize the space and time complexity. 
 Input Format:
The first and the only argument of input contains a 2-d integer matrix, A, of size M x N.
Output Format:
Return a 2-d matrix that satisfies the given conditions.
Constraints:
1 <= N, M <= 1000
0 <= A[i][j] <= 1
Examples:
Input 1:
    [   [1, 0, 1],
        [1, 1, 1], 
        [1, 1, 1]   ]

Output 1:
    [   [0, 0, 0],
        [1, 0, 1],
        [1, 0, 1]   ]

Input 2:
    [   [1, 0, 1],
        [1, 1, 1],
        [1, 0, 1]   ]

Output 2:
    [   [0, 0, 0],
        [1, 0, 1],
        [0, 0, 0]   ] */

    
    void Solution::setZeroes(vector<vector<int> > &A) {
    // Do not write main() function.
    // Do not read input, instead use the arguments to the function.
    // Do not print the output, instead return values as specified
    // Still have a doubt. Checkout www.interviewbit.com/pages/sample_codes/ for more details
    unordered_set<int> rows, cols;
    
    for(int i=0;i<A.size();i++){
        for(int j=0; j<A[i].size();j++){
            
            if(A[i][j]==0){
                rows.insert(i);
                cols.insert(j);
            }
            
        }
    }
    
    for(int i=0;i<A.size();i++){
        for(int j=0;j<A[i].size();j++){
            if(rows.find(i)!=rows.end() || cols.find(j)!=cols.end()){
                A[i][j]=0;
            }
        }
    }
}