http://beginnerust.blogspot.hk/2016/10/codeforce725d.html

codeforce725D.cpp

#include <bits/stdc++.h>
#define N 300000+5
#define ll long long
#define INF 2147483647
using namespace std;
int n,place;
ll hv,b,w;
typedef pair<ll,ll> P;
priority_queue<P> sml;
priority_queue<ll,vector<ll>,greater<ll> > bg;
int main(){
   scanf("%d",&n); n--;
   scanf("%I64d%I64d",&hv,&w);
   place=1;
   for(int i=0;i<n;i++){
    scanf("%I64d%I64d",&b,&w);
    if(b<=hv) sml.push(P(b,w));
    else bg.push(w-b+1),place++;
   }
   while(!bg.empty() && bg.top()<=hv){
    hv-=bg.top();
    bg.pop();
    while(!sml.empty() && hv<sml.top().first) {
        bg.push(sml.top().second-sml.top().first+1);
        sml.pop();
    }
    if(place>bg.size()+1) place=bg.size()+1;
    }
   printf("%d\n",place);
}