A39 反悔贪心 CF865D Buy Low Sell High

#include <iostream>
#include <cstring>
#include <algorithm>
#include <queue>
using namespace std;

const int N=300005;
int n,p[N];
long long ans;
priority_queue<int,vector<int>
                  ,greater<int> > q;

int main(){
  cin>>n;
  for(int i=1; i<=n; i++) cin>>p[i];
  
  for(int i=1; i<=n; i++){
    if(!q.empty()&&q.top()<p[i]){
      ans+=(p[i]-q.top()); 
      q.pop();      //卖出pt
      q.push(p[i]); //买入pi (为了反悔)
    }
    q.push(p[i]);   //买入pi (为了交易)
  }
  cout<<ans<<endl;
  return 0;
}