Set_Matrix_Zeroes.cpp

class Solution {
public:
    void setZeroes(vector<vector<int> > &matrix) {
        // O(m + n) extra space
        /*
        int n = matrix.size();
        if(n == 0) return;
        int m = matrix[0].size();
        if(m == 0) return;
        bool row[n + 1], col[m + 1];
        memset(row, false, sizeof row);
        memset(col, false, sizeof col);
        for(int i = 0; i < n; ++i) {
            for(int j = 0; j < m; ++j) {
                if(matrix[i][j] == 0) {
                    row[i] = true, col[j] = true;
                }
            }
        }
        for(int i = 0; i < n; ++i) {
            if(row[i]) for(int j = 0; j < m; ++j) matrix[i][j] = 0;
        }
        for(int i = 0; i < m; ++i) {
            if(col[i]) for(int j = 0; j < n; ++j) matrix[j][i] = 0;
        }
        */
            
        // O(1) (constant) space
        int row = matrix.size();
        if (row == 0) return;
        int col = matrix[0].size();
        if (col == 0)return;
         
        bool fc0 = false;
        bool fr0 = false;
         
        for (int i = 0; i < col; i++) {
            if (matrix[0][i] == 0) { 
                fr0 = true;
                break;
            }
        }
         
        for (int i = 0; i < row; i++) {
            if (matrix[i][0] == 0) { 
                fc0 = true; 
                break;
            }
        }
         
        for (int i = 1; i < row; i++) {
            for (int j = 1; j < col; j++) {
                if (matrix[i][j] == 0) {
                    matrix[i][0] = 0;
                    matrix[0][j] = 0;
                }
            }
        }
         
         
        for (int i = 1;i < col; i++) {
            if (matrix[0][i] == 0) {
                for(int j = 0; j < row; j++) {
                    matrix[j][i] = 0;
                }
            }
        }
         
        for (int i = 1;i < row; i++) {
            if (matrix[i][0] == 0) {
                for(int j = 0; j <col; j++) {
                    matrix[i][j] = 0;
                }
            }
        }
         
        if (fr0) {
            for (int i = 0;i < col; i++) matrix[0][i] = 0;
        }
        if (fc0) {
            for (int i = 0; i < row; i++) matrix[i][0] = 0;
        }
    }
};