POJ 2431 Expedition——贪心

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <queue>
using namespace std;
const int maxn = 1e6 + 5;
struct Data { int a, b; } data[10005];
int N, L, P, road[maxn];

int main() {
    while (~scanf("%d", &N)) {
        memset(road, 0, sizeof(road));
        for (int i = 1; i <= N; i++) scanf("%d %d", &data[i].a, &data[i].b);
        scanf("%d %d", &L, &P);
        for (int i = 1; i <= N; i++) {
            road[L - data[i].a] = data[i].b;
        }
        priority_queue<int> q;
        int ans = 0;
        for (int i = 0; i <= L; i++) {
            if (i > P) {
                if (q.empty()) break;
                P += q.top(); q.pop();
                ans++;
            }
            if (road[i]) q.push(road[i]);
        }
        if (P < L) printf("-1\n");
        else printf("%d\n", ans);
    }
    return 0;
}