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+;
 const ll mod=1e9+;
 #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=;i<=n;i++)
     {
         scanf("%lld",&a);
         f.push(make_pair(a,i));
         if (i>k)
             f.pop();
     }
     g=;
     while (!f.empty())
     {
         pr[g]=f.top();
         g++;
         f.pop();
     }
     sort(pr,pr+g,cmp1);
     for (i=;i<g;i++)
         printf("%lld\n",pr[i].first);
     return ;
 }