g0001_0100.s0073_set_matrix_zeroes.Solution.cpp Maven / Gradle / Ivy

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104 LeetCode algorithm problem solutions

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// #Medium #Top_100_Liked_Questions #Top_Interview_Questions #Array #Hash_Table #Matrix
// #Udemy_2D_Arrays/Matrix #Big_O_Time_O(m*n)_Space_O(1)
// #2024_05_26_Time_7_ms_(83.11%)_Space_16.5_MB_(34.88%)

#include 

class Solution {
public:
    void setZeroes(std::vector>& matrix) {
        int m = matrix.size();
        int n = matrix[0].size();
        bool row0 = false;
        bool col0 = false;

        // Check if 0th column needs to be marked all 0s in the future
        for (int i = 0; i < m; i++) {
            if (matrix[i][0] == 0) {
                col0 = true;
                break;
            }
        }

        // Check if 0th row needs to be marked all 0s in the future
        for (int j = 0; j < n; j++) {
            if (matrix[0][j] == 0) {
                row0 = true;
                break;
            }
        }

        // Store the signals in the 0th row and column
        for (int i = 1; i < m; i++) {
            for (int j = 1; j < n; j++) {
                if (matrix[i][j] == 0) {
                    matrix[i][0] = 0;
                    matrix[0][j] = 0;
                }
            }
        }

        // Mark 0 for all cells based on signals from the 0th row and 0th column
        for (int i = 1; i < m; i++) {
            for (int j = 1; j < n; j++) {
                if (matrix[i][0] == 0 || matrix[0][j] == 0) {
                    matrix[i][j] = 0;
                }
            }
        }

        // Set 0th column
        if (col0) {
            for (int i = 0; i < m; i++) {
                matrix[i][0] = 0;
            }
        }

        // Set 0th row
        if (row0) {
            for (int j = 0; j < n; j++) {
                matrix[0][j] = 0;
            }
        }
    }
};