SCU 2401 *** The Story Of Finding Love

#pragma warning(disable:4996)
#include<iostream>
#include<cstdio>
#include<cmath>
#include<stack>
#include<queue>
#include<cstring>
#include<sstream>
#include<set>
#include<string>
#include<iterator>
#include<vector>
#include<map>
#include<algorithm>
using namespace std;struct p {int d, w;
}s[100010];
int cmp(p a, p b) {return a.d < b.d;
}
int main(void) {int n, D, W;while (cin >> n) {cin >> D >> W;for (int i = 0; i < n; ++i)cin >> s[i].d >> s[i].w;s[n].d = D, s[n++].w = 0;//将终点也加进去，避免最后处理终点的问题sort(s, s + n, cmp);priority_queue<int> p;//优先队列int rest = W, ans = 0;//rest为目前水量，ans为最终结果for (int i = 0; i < n; ++i) {if (rest >= s[i].d)//rest够到下一个加油站，则将下一个加油站的油量加入队列中p.push(s[i].w);else {while (rest < s[i].d) {//不够到下一个加油站，则一直加前面的加油站中的油，直到够if (p.empty()) {ans = -1; break;//前面所有的加油站的油都加完了还是不够，那么水哥阵亡}rest += p.top();p.pop();ans++;}p.push(s[i].w);}if (ans == -1)break;}cout << ans << endl;}return 0;
}