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73. Set Matrix Zeroes

Medium

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

Follow up:

• A straightforward solution using O(mn) space is probably a bad idea.
• A simple improvement uses O(m + n) space, but still not the best solution.
• Could you devise a constant space solution?

Solution

/*
 Do not return anything, modify matrix in-place instead.
 */
function setZeroes(matrix: number[][]): void { //NOSONAR
    const cols: number[] = []
    const rows: number[] = []
    for (let i = 0; i < matrix.length; i++) {
        for (let j = 0; j < matrix[i].length; j++) {
            if (matrix[i][j] === 0) {
                if (!rows.includes(i)) rows.push(i)
                if (!cols.includes(j)) cols.push(j)
            }
        }
    }
    for (const row of matrix) {
        for (const col of cols) {
            row[col] = 0
        }
    }
    for (let j = 0; j < rows.length; j++) {
        for (let i = 0; i < matrix[j].length; i++) {
            matrix[rows[j]][i] = 0
        }
    }
}

export { setZeroes }

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