73. Set Matrix Zeroes

Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in place.

click to show follow up.

Follow up:

Did you use extra space?

A straight forward 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?

constant space.

public class Solution {
    public void setZeroes(int[][] matrix) {
        if(matrix == null || matrix.length == 0 || matrix[0].length == 0) return;
        boolean resetFirstRow = false;
        boolean resetFirstColumn = false;
        for(int i=0; i< matrix.length;i++){
            if(matrix[i][0] == 0) resetFirstColumn = true;
        }
        for(int i=0; i< matrix[0].length;i++){
            if(matrix[0][i] == 0) resetFirstRow = true;
        }

        for(int i=1; i<matrix.length;i++){
            for(int j=1; j< matrix[0].length; j++){
                if(matrix[i][j] == 0){
                    matrix[i][0] = 0;
                    matrix[0][j] =0;
                }
            }
        }
        for(int i=1; i<matrix.length;i++){
            for(int j=1; j< matrix[0].length; j++){
                if(matrix[i][0] == 0 || matrix[0][j] == 0){
                    matrix[i][j] = 0;
                }
            }
        }

        if(resetFirstColumn){
            for(int i=0; i<matrix.length;i++){
                matrix[i][0] = 0;
            }
        }
        if(resetFirstRow){
            for(int i=0;i<matrix[0].length; i++){
                matrix[0][i] = 0;
            }
        }
    }
}