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.

题目大意：给定一个矩阵，将0所在的行和列的所有元素智0，要求就地替换

题目难度：Medium

/**
 * Created by gzdaijie on 16/5/30
 * 复杂度O(N * M)
 */
public class Solution {
    public void setZeroes(int[][] matrix) {
        if (matrix == null || matrix.length == 0) return;
        if (matrix[0].length == 0) return;

        int m = matrix.length;
        int n = matrix[0].length;
        // flag[0...m-1]标记行, flag[m...m + n - 1]标记列
        boolean[] flag = new boolean[m + n];

        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                if (matrix[i][j] != 0) continue;
                flag[i] = flag[m + j] = true;
            }
        }
        // 行置为0
        for (int i = 0; i < m; i++) {
            if (!flag[i]) continue;
            for (int j = 0; j < n; j++) matrix[i][j] = 0;
        }
        // 列置为0
        for (int i = 0; i < n; i++) {
            if (!flag[m + i]) continue;
            for (int j = 0; j < m; j++) matrix[j][i] = 0;
        }
    }
}