求n个数中前k个数，按之前的顺序输出(HK IPM)

For smaller k：

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <list>
#include <stack>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <algorithm>
#include <iostream>
using namespace std;
#define ll long long
const long maxn=1e6+5;
const ll mod=1e9+7;
#define inf 1e9

struct cmp
{
    bool operator() (pair<long long,long> a,pair<long long,long> b)
    {
        return a.first < b.first;
    }
};

bool cmp1(pair<long long,long> a,pair<long long,long> b)
{
    return a.second < b.second;
}

priority_queue<pair<long long,long>,vector<pair<long long,long> >, cmp> f;
pair<long long,long> pr[maxn];

int main()
{
    long n,k,i,g;
    long long a;
    scanf("%ld%ld",&n,&k);
    for (i=1;i<=n;i++)
    {
        scanf("%lld",&a);
        f.push(make_pair(a,i));
        if (i>k)
            f.pop();
    }
    g=0;
    while (!f.empty())
    {
        pr[g]=f.top();
        g++;
        f.pop();
    }
    sort(pr,pr+g,cmp1);
    for (i=0;i<g;i++)
        printf("%lld
",pr[i].first);
    return 0;
}