leetcode：1252. 奇数值单元格的数目

链接：https://leetcode-cn.com/problems/cells-with-odd-values-in-a-matrix/
记录每个行与列被增加的次数，最终为奇数的个数为
$增加奇数次的行数\ast m+增加奇数次的列数\ast n-重叠的部分$
C++代码：

class Solution {
     
public:
    int oddCells(int n, int m, vector<vector<int>>& indices) {
     
        int len = max(n,m);
        vector<vector<int>> record(2, vector<int>(len,0));
        for(int i = 0;i<indices.size();i++)
        {
     
            record[0][indices[i][0]]^=1;
            record[1][indices[i][1]]^=1;
        }
        int row = 0,col = 0;
        for(int i = 0;i<n;i++)
            if(record[0][i]==1)
                row++;
        for(int i = 0;i<m;i++)
            if(record[1][i]==1)
                col++;
        
        return row*m+col*n-2*row*col;
    }
};