力扣2356.二维差分模板——子矩阵元素加1

• 模板题

  • 
  • 最后将n+2*n+2的矩阵删去周围一圈变成n*n矩阵的操作

•   class Solution {
    public:
        vector<vector<int>> rangeAddQueries(int n, vector<vector<int>>& queries) {
            vector<vector<int>> res(n+2,vector<int>(n+2));
            for(auto t : queries)
            {
                int r1=t[0],c1=t[1],r2=t[2]+1,c2=t[3]+1;
                res[r1+1][c1+1] ++; 
                res[r1+1][c2+1] --;
                res[r2+1][c1+1] --;
                res[r2+1][c2+1] ++;
            }
            for(int i=1;i<=n;i++)
                for(int j=1;j<=n;j++)
                    res[i][j] += res[i][j-1] + res[i-1][j] - res[i-1][j-1];
            //删上下两边
            res.pop_back() , res.erase(res.begin());
            //每一行删去头尾
            for(auto &row:res)
                row.pop_back(),row.erase(row.begin());
            return res;
        }
    };