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?

 

public class Solution {
    public void setZeroes(int[][] matrix) {
        if(matrix == null || matrix.length == 0 || matrix[0].length == 0) return;
        int row = 0, col = 0;
        boolean sig = true;
        for(int i = 0; i < matrix.length; i ++){
            for(int j = 0; j < matrix[0].length; j ++){
                if(matrix[i][j] == 0){
                    if(sig){
                        row = i;
                        col = j;
                        sig = false;
                    } else {
                        matrix[row][j] = 0;
                        matrix[i][col] = 0;
                    }
                }
            }
        }
        if(sig) return;
        for(int i = 0; i < matrix.length; i ++){
            for(int j = 0; j < matrix[0].length; j ++){
                if((matrix[row][j] == 0 || matrix[i][col] == 0) && i != row && j != col) matrix[i][j] = 0;
            }
        }
        for(int i = 0; i < matrix.length; i ++){
            matrix[i][col] = 0;
        }
        for(int j = 0; j < matrix[0].length; j ++){
            matrix[row][j] = 0;
        }
    }
}