Set-matrix-zeroes

 

題目描述

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(m n) 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?

 

import java.util.*;
public class Solution {
    public void setZeroes(int[][] matrix) {
        if(matrix == null || matrix.length == 0|| matrix[0].length == 0)
            return ;
        ArrayList<Integer> row = new ArrayList<>();
        ArrayList<Integer> column = new ArrayList<>();
        for(int i = 0;i < matrix.length;i++){
            for(int j = 0;j < matrix[0].length;j++){
                if(matrix[i][j] == 0){
                    row.add(i);
                    column.add(j);
                }
            }
        }
        for(Integer a:row){
            for(int i = 0 ; i < matrix[0].length;i++){
                matrix[a][i] = 0;
            }
        }
        for(Integer b : column){
            for(int j = 0;j < matrix.length;j++){
                matrix[j][b] = 0;
            }
        }
    }
}