学步园

#include<cstdlib>
#include<iostream>
#include<sstream>
#include<cstdio>
#include<cmath>
#include<cstring>
#include <algorithm>
#include<vector>
#include<set>
#include<queue>
#define LL long long
#define inf 0x7fffffff
#define E 1e-9
#define M 100
#define N 10005
using namespace std;
int n,p[N],d[N],sub[N];

bool cmp(int i,int j)
{
  return d[i]<d[j];
}
int main()
{
#ifndef ONLINE_JUDGE
  freopen("ex.in","r",stdin);
#endif
  while(scanf("%d",&n)!=EOF)
    {
      if(!n)
        {
          printf("0\n");
          continue;
        }
      for(int i=0; i<n; i++)
        sub[i]=i;
      for (int i=0; i<n; i++)
        {
          scanf("%d%d",&p[i],&d[i]);
        }
      sort(sub,sub+n,cmp);
      priority_queue<int,vector<int>,less<int> > q;
      int pre=d[sub[n-1]];
      int sum=0;
      for(int i=n-1; i>=0; i--)
        {
          int j=sub[i];
          if(d[j]==pre)
            {
              q.push(p[j]);
            }
          else
            {
              int k=0;
              while(!q.empty()&&k<pre-d[j])
                {
                  sum+=q.top();
                  q.pop();
                  k++;
                }
              pre=d[j];
              q.push(p[j]);
            }
        }
      int k=0;
      while(!q.empty()&&k<pre-0)
        {
          sum+=q.top();
          q.pop();
          k++;
        }
      printf("%d\n",sum);
    }

  return 0;
}