Set Matrix Zeroes

Problem

Given an m x n integer matrix matrix, if an element is 0, set its entire row and column to 0's, and return the matrix.

You must do it in place.

Example 1:

Input: matrix = [[1,1,1],[1,0,1],[1,1,1]]
Output: [[1,0,1],[0,0,0],[1,0,1]]

Example 2:

Input: matrix = [[0,1,2,0],[3,4,5,2],[1,3,1,5]]
Output: [[0,0,0,0],[0,4,5,0],[0,3,1,0]]

Constraints:

m == matrix.length
n == matrix[0].length
1 <= m, n <= 200
-2³¹ <= matrix[i][j] <= 2³¹ - 1

Solution

/**
 * @param {number[][]} matrix
 * @return {void} Do not return anything, modify matrix in-place instead.
 */
var setZeroes = function(matrix) {
    let col0 = false;
    let row0 = false;
    const m = matrix.length;
    const n = matrix[0].length;

    // check if 0th col has any zeroes
    for (let i = 0; i < m; i++) {
        if (!matrix[i][0]) {
            col0 = true;
            break;
        }
    }

    // check if 0th row has any zeroes
    for (let j = 0; j < n; j++) {
        if (!matrix[0][j]) {
            row0 = true;
            break;
        }
    }

    // check if non 0th rows and cols have any zeroes
    for (let i = 1; i < m; i++) {
        for (let j = 1; j < n; j++) {
            if (!matrix[i][j]) {
                matrix[0][j] = 0;
                matrix[i][0] = 0;
            }
        }
    }

    // set non 0th row of zero entries
    for (let i = 1; i < m; i++) {
        if (!matrix[i][0]) {
            for (let j = 1; j < n; j++) {
                matrix[i][j] = 0;
            }
        }
    }

    // set non 0th cols of zero entries
    for (let j = 1; j < n; j++) {
        if (!matrix[0][j]) {
            for (let i = 1; i < m; i++) {
                matrix[i][j] = 0;
            }
        }
    }

    // set 0th cols of zero entries
    if (col0) {
        for (let i = 0; i < m; i++) {
            matrix[i][0] = 0;
        }
    }

    // set 0th col of zero entries
    if (row0) {
        for (let j = 0; j < n; j++) {
            matrix[0][j] = 0;
        }
    }
};
};

We will use the 0th column and 0th row to keep track of whether a row or column needs to be set to all zeroes (eg. if the 0th row and 6th column is 0, then this tells us we need to set the entire 6th column to zeroes). Note that we must first test if the 0th row or 0th column have zeroes themselves before any modification.

Problem​

Solution​

Problem

Solution