求助 P4995 跳跳！

#include<bits/stdc++.h>
using namespace std;
int n;
long long ans,a[305],z;
int main(){
	ios::sync_with_stdio(0);
	cin>>n;
	for(int i=1;i<=n;i++)cin>>a[i];
	sort(a+1,a+1+n);
	int x=n,y=1;
	while(x>y){
		ans+=(a[x]-z)*(a[x]-z);
		ans+=(z-a[y])*(z-a[y]);
		z=a[y],x--,y++;
	}
	if(x==y)ans+=(a[x]-z)*(a[x]-z);
	cout<<ans;
	return 0;
}