Leetcode:Set Matrix Zeroes 矩阵置0

戳我去解题

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

 

这题还是很简单的，就是有点坑，遍历矩阵的时候，每遇到0的时候，我们不能立即将所在行和列置0，否则，到最后矩阵所有值都为0了，

而应该将所在的行和列号存储起来，最后遍历完矩阵之后，再根据所存储的行列号来置0

class Solution {

public:

    void setZeroes(vector<vector<int> > &matrix) {

        int row = matrix.size();

        int col = matrix.at(0).size();

        set<int> rowZeros;  

        set<int> colZeros;

        for (int i = 0; i < row; ++i) {

            for (int j = 0; j < col; ++j) {

                if (matrix.at(i).at(j) == 0) {

                    rowZeros.insert(i);

                    colZeros.insert(j);

                }

            }

        }

        for (auto iter = rowZeros.begin(); iter != rowZeros.end(); ++iter) {

            fill(matrix.at(*iter).begin(), matrix.at(*iter).end(), 0);

        }

        for (auto iter = colZeros.begin(); iter != colZeros.end(); ++iter) {

            for (int j = 0; j < row; ++j) {

                matrix.at(j).at(*iter) = 0; 

            }

        }

    }

};