priority_queue practice

最新推荐文章于 2025-11-08 16:25:21 发布

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本文通过两个实例介绍如何运用C++ STL中的优先队列解决典型算法问题，包括旅行加油问题和绳子连接问题。文章提供了完整的代码实现，并解释了优先队列的基本用法及其在解决实际问题中的应用。

https://vjudge.net/problem/POJ-2431

http://stackoverflow.com/questions/15601973/stl-priority-queue-of-c-with-struct

#include<iostream>
#include<cstdio>
#include<string.h>
#include<math.h>
#include<string>
#include<map>
#include<set>
#include<vector>
#include<algorithm>
#include<queue>
#include<iomanip>
using namespace std;
const int INF = 0x3f3f3f3f;
const int NINF = 0xc0c0c0c0;

struct S{
    int dis,fuel;
}stop[10005];
bool cmp(S a,S b){
    return a.dis < b.dis;
}
int main()
{
    int n;
    while(cin >> n){
        for(int i=0;i<n;i++){
            cin >> stop[i].dis >> stop[i].fuel;
        }
        int fdis,lfuel;
        cin >> fdis >> lfuel;
        for(int i=0;i<n;i++){
            stop[i].dis = fdis - stop[i].dis;
        }
        sort(stop,stop+n,cmp);
        priority_queue<int> pq;
        int k = 0;
        while(k <n && stop[k].dis <= lfuel){
            pq.push(stop[k].fuel);
            k++;
        }
        int cnt = 0;
        int flag = 0;
        while(!pq.empty()){
            if(lfuel >= fdis){
                cout << cnt << endl;
                flag = 1;
                break;
            }
            int temp = pq.top();
            pq.pop();
            cnt++;
            lfuel += temp;
            while(k<n && stop[k].dis <= lfuel){
                pq.push(stop[k].fuel);
                k++;
            }
        }
        if(flag == 0){
            cout << -1 << endl;
        } 
    }
}

https://vjudge.net/problem/POJ-3253

http://en.cppreference.com/w/cpp/container/priority_queue

#include<iostream>
#include<cstdio>
#include<string.h>
#include<math.h>
#include<string>
#include<map>
#include<set>
#include<vector>
#include<algorithm>
#include<queue>
#include<iomanip>
using namespace std;
const int INF = 0x3f3f3f3f;
const int NINF = 0xc0c0c0c0;

int main()
{
    int n;
    int len[20005];
    while(cin >> n){
        for(int i=0;i<n;i++){
            cin >> len[i];
        }
        priority_queue<int,vector<int>,greater<int> > pq;
        for(int i=0;i<n;i++){
            pq.push(len[i]);
        }
        long long  ans = 0;
        while(pq.size() > 1){
            int l1,l2;
            l1 = pq.top();
            pq.pop();
            l2 = pq.top();
            pq.pop();
            pq.push(l1+l2);
            ans += l1+l2;
        }
        cout << ans << endl;
    }
}