C++ 解法, 执行用时: 107ms, 内存消耗: 7800K, 提交时间: 2022-06-26 13:55:35

// USACO 2020 Feb S. Triangles
#include <bits/stdc++.h>
using namespace std;
const int MOD = 1e9 + 7, CC = 1e4;
#define _for(i, a, b) for (int i = (a); i < (int)(b); ++i)
using LL = long long;
struct Item {
  int v, i;
  bool operator<(const Item& x) const {
    if (v != x.v) return v < x.v;
    return i < x.i;
  }
};
int main() {
  int n;
  cin >> n;
  map<int, vector<Item>> XY, YX;
  for (int i = 0, x, y; i < n; i++)
    cin >> x >> y, XY[x + CC].push_back({y, i}), YX[y + CC].push_back({x, i});
  vector<LL> hs(n), bs(n);
  for (auto& p : XY) {
    auto& Y = p.second;
    int sz = Y.size();
    sort(Y.begin(), Y.end());
    hs[Y[0].i] = 0;
    _for(j, 1, sz) hs[Y[0].i] += Y[j].v - Y[0].v;
    _for(j, 1, sz) hs[Y[j].i] =
        hs[Y[j - 1].i] + (2 * j - sz) * (Y[j].v - Y[j - 1].v);
  }
  for (auto& p : YX) {
    auto& X = p.second;
    int sz = X.size();
    sort(X.begin(), X.end());
    bs[X[0].i] = 0;
    _for(j, 1, sz) bs[X[0].i] += X[j].v - X[0].v;
    _for(j, 1, sz) bs[X[j].i] =
        bs[X[j - 1].i] + (2 * j - sz) * (X[j].v - X[j - 1].v);
  }
  LL ans = 0;
  _for(i, 0, n)(ans += hs[i] * bs[i] % MOD) %= MOD;
  cout << ans << '\n';
}