题解

求点赞（凑五十个）

#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;

struct Truck {
    long long a, b, d;
};

bool cmp_truck(const Truck &u, const Truck &v) {
    return u.d > v.d;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n, m, x;
    cin >> n >> m >> x;

    vector<pair<int, int>> stations(n); // (p, c)
    for (int i = 0; i < n; i++) {
        cin >> stations[i].first >> stations[i].second;
    }
    sort(stations.begin(), stations.end()); // 按位置从小到大

    vector<Truck> trucks(m);
    for (int i = 0; i < m; i++) {
        cin >> trucks[i].a >> trucks[i].b;
        trucks[i].d = trucks[i].a - trucks[i].b;
    }
    sort(trucks.begin(), trucks.end(), cmp_truck); // 按 d 降序

    long long ans = 0;
    int left = 0, right = n - 1;
    for (int i = 0; i < m; i++) {
        long long d = trucks[i].d;
        if (d >= 0) {
            // 从左边取最小的 p
            while (left <= right && stations[left].second == 0) left++;
            if (left > right) break;
            ans += 2LL * stations[left].first * d;
            stations[left].second--;
        } else {
            // 从右边取最大的 p
            while (left <= right && stations[right].second == 0) right--;
            if (left > right) break;
            ans += 2LL * stations[right].first * d;
            stations[right].second--;
        }
        // 加上常数 2 * b * x
        ans += 2LL * trucks[i].b * x;
    }

    cout << ans << endl;
    return 0;
}