p73

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LeetCode p73 Set Matrix Zeroes 题解

1.题目：

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

题意：

给一个矩阵，把有0的行列全部设置为0.

2.解题思路:

见代码

3.代码

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public class Solution {
    public void setZeroes(int[][] matrix) {
        int n = matrix.length;
		if (n < 1)
			return;
		int m = matrix[0].length;
		if (m < 1)
			return;
		HashSet<Integer> n1 = new HashSet<Integer>();
		HashSet<Integer> m1 = new HashSet<Integer>();
		for (int i = 0; i < n; i++) {
			for (int j = 0; j < m; j++) {
				if (matrix[i][j] == 0) {
					n1.add(i);
					m1.add(j);
				}
			}
		}
		for (int i = 0; i < n; i++) {
			for (int j = 0; j < m; j++) {

				if (n1.contains(i) || m1.contains(j)) {
					matrix[i][j] = 0;
				}
			}
		}
    }
}

4.一些总结：