leetcode73 矩阵置零

要点在于分成两部分标记，负责第一行和第一列的标记/其余部分的标记，注意(0,0)是特殊位置，应该特殊处理

class Solution {
public:
    void setZeroes(vector<vector<int>>& matrix) {
        if(matrix.empty()) return;
        int l0 = 1, r0 = 1;
        for(int i = 0; i < matrix.size(); ++i) if(matrix[i][0] == 0) r0 = 0;
        for(int i = 0; i < matrix[0].size(); ++i) if(matrix[0][i] == 0) l0 = 0;
        
        for(int i = 1; i < matrix.size(); ++i)
            for(int j = 1; j < matrix[0].size(); ++j)
                if(matrix[i][j] == 0) matrix[i][0] = matrix[0][j] = 0;
        
        for(int i = 1; i < matrix.size(); ++i)
            if(matrix[i][0] == 0) for(int k = 1; k < matrix[i].size(); ++k) matrix[i][k] = 0;
        
        for(int i = 0; i < matrix[0].size(); ++i)
            if(matrix[0][i] == 0) for(int k = 1; k < matrix.size(); ++k) matrix[k][i] = 0;
        
        if(l0 == 0) for(int i = 0; i < matrix[0].size(); ++i) matrix[0][i] = 0;
        if(r0 == 0) for(int i = 0; i < matrix.size(); ++i) matrix[i][0] = 0;
    }
};