RT样例全过

#include<bits/stdc++.h>
#define ll long long
#define WA AC
using namespace std;
ll a[1000001];
int main(){
	int n;
	cin>>n;
	for(int i=1;i<=n;i++)
	{
		cin>>a[i];
		//cout<<a[i]<<" ";
	}
	//cout<<endl;
	sort(a+1,a+n+1,greater<int>( ));
	/*for(int i=1;i<=n;i++)
	{
		cout<<a[i]<<" ";
	}
	cout<<endl;*/ 
	ll i=1,i1=0,i2=0,s=0;
	while(1) 
	{
		s++;
		//cout<<s<<" "<<i<<" "<<i1<<" "<<i2<<endl;;
		if(i1==0)
		{
			i1+=a[i]-1;
			//cout<<i1<<" "<<i<<endl;
			i++;
			
		}
		else i1--;
		if(i2==0)
		{
			i2+=a[i]-1;
			//cout<<i2<<" "<<i<<endl;
			i++;
		}
		else i2--;
		if(i1<=0&&i2<=0&&i>=n) break;
	}
	cout<<s;
	return 0;
}