poj 2431 Expedition

优先队列，工具而已。

先把加油站按照距离排序，然后按照油量大小加入优先队列

#include<cstdio>
#include<iostream>
#include<cstring>
#include<algorithm>
#include<queue>
#include<vector>
using namespace std;
struct sb
{
    int f;
    int d;
}way[10010];
bool cmp(sb a,sb b)
{
    return a.d>b.d;
}
priority_queue<int>q;
int main()
{
    int n;
    while(scanf("%d",&n)==1)
    {
        for(int i=1;i<=n;i++)
        {
            cin>>way[i].d>>way[i].f;
        }
        sort(way+1,way+n+1,cmp);
        int d,f;
        cin>>d>>f;
        q.push(f);
        int cnt=-1;
        int i=1;
        while(!q.empty()&&d>0)
        {
            d=d-q.top();
            q.pop();
            cnt++;
            while(d<=way[i].d&&i<=n)
            {
                q.push(way[i].f);
                i++;
            }
        }
        if(d<=0)
            cout<<cnt<<endl;
        else
            cout<<-1<<endl;
    }
    return 0;
}