#include<bits/stdc++.h>
using namespace std;
int mp[111][111];
int main(){
    int n, ans = 0;
    cin >> n;
    for (int i = 1; i <= n; i ++){
        int x1, y1, x2, y2; cin >> x1 >> y1 >> x2 >> y2;
        for (int k = x1; k <= x2; k ++){
            for (int j = y1; j <= y2;j ++){
                mp[k][j] += 1;
            }
        }
    }
    for (int i = 0; i <= 100; i ++){
        for (int j = 0; j <= 100; j ++){
            if (mp[i][j]) ans ++;
        }
    }
    cout << ans;
    return 0;
}

::::info[我的问题]{open} 把代码中高亮的部分换成

for (int k = x1; k < x2; k ++){
  for (int j = y1; j < y2;j ++){

就可以了
::::

::::success[请教]{open} 大佬求调