g0001_0100.s0073_set_matrix_zeroes.Solution Maven / Gradle / Ivy

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package g0001_0100.s0073_set_matrix_zeroes;

// #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_11_11_Time_0_ms_(100.00%)_Space_45.6_MB_(50.86%)

public class Solution {
    // Approach: Use first row and first column for storing whether in future
    //           the entire row or column needs to be marked 0
    public void setZeroes(int[][] matrix) {
        int m = matrix.length;
        int n = matrix[0].length;
        boolean row0 = false;
        boolean col0 = false;
        // Check if 0th col needs to be market all 0s in future
        for (int[] ints : matrix) {
            if (ints[0] == 0) {
                col0 = true;
                break;
            }
        }
        // Check if 0th row needs to be market all 0s in future
        for (int i = 0; i < n; i++) {
            if (matrix[0][i] == 0) {
                row0 = true;
                break;
            }
        }
        // Store the signals in 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 signal from 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
        for (int i = 0; i < m; i++) {
            if (col0) {
                matrix[i][0] = 0;
            }
        }
        // Set 0th row
        for (int i = 0; i < n; i++) {
            if (row0) {
                matrix[0][i] = 0;
            }
        }
    }
}