ac 796子矩阵的和

求左上矩阵的和

      #include<bits/stdc++.h>
      using namespace std;
      int main() {
      #ifdef ONLINE_JUDGE
      #else
          freopen("D:\\Hello world\\编程输入2\\in.txt", "r", stdin);
      #endif
          int n, m, q;
          cin >> n >> m >> q;
          vector<vector<int>> nums;
          for (int i =0; i < n; i++) {
              vector<int> temp;
              nums.push_back(temp);
              for (int j = 0; j < m; j++) {
                  int tempNum;
                  cin >> tempNum;
                  if (i == 0 && j != 0) {
                      tempNum = nums[i][j - 1] + tempNum;
                  }
                  else if (j == 0 && i != 0) {
                      tempNum = nums[i - 1][j] + tempNum;
                  }
                  else if (j != 0 && i != 0) {
                      tempNum = nums[i - 1][j] + nums[i][j - 1] + tempNum - nums[i - 1][j - 1];
                  }
                  nums[i].push_back(tempNum);
              }
          }
          for (int i = 0; i < q; i++) {
              int x1, y1, x2, y2;
              cin >> x1 >> y1 >> x2 >> y2;
              if (x1 == 1 && y1 == 1) {
                  cout << nums[x2 - 1][y2 - 1] << endl;
              }
              else if (x1 == 1 && y1 != 1) {
                  cout << (nums[x2 - 1][y2 - 1] - nums[x2 - 1][y1 - 2]) << endl;
              }
              else if (x1 != 1 && y1 == 1) {
                  cout << (nums[x2 - 1][y2 - 1] - nums[x1 - 2][y2 - 1]) << endl;
              }
              else {
                  cout << (nums[x2 - 1][y2 - 1] - nums[x1 - 2][y2 - 1] - nums[x2 - 1][y1 - 2] + nums[x1 - 2][y1 - 2]) << endl;
              }
          }
      }