[LeetCode]Set Matrix Zeroes

题目描述:(链接)

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?

解题思路：

定义两个数组分别记录某一行或者某一列是否包含0。

class Solution {
public:
    void setZeroes(vector<vector<int>>& matrix) {
        int rows = matrix.size();
        int cols = matrix[0].size();
        
        vector<bool> rowsVec(rows, false);
        vector<bool> colsVec(cols, false);
        
        for (int i = 0; i < rows; ++i) {
            for (int j = 0; j < cols; ++j) {
                if (matrix[i][j] == 0) {
                    rowsVec[i] = true;
                    colsVec[j] = true;
                    continue;
                }
            }
        }
        
        for (int i = 0; i < rows; ++i) {
            if (rowsVec[i]) {
                fill(&matrix[i][0], &matrix[i][0] + cols, 0);
            }
        }
        
        for (int j = 0; j < cols; ++j) {
            if (colsVec[j]) {
                for (int i = 0; i < rows; ++i) {
                    matrix[i][j] = 0;
                }
            }
        }
    }
};