RT，求程序的解析

#include <bits/stdc++.h>
using namespace std;
int n,a[310];
int calc(int l,int r){
	int i,ans,tmp;
	if (l>r) return 0;
	ans=calc(l+1,r)+(r-l+1)*(r-l+1)*a[l];
	for (i=l+1;i<=r;i++)
	{
		tmp=calc(l,i-1)+calc(i+1,r)+(r-l+1)*(r-l+1)*a[i];
		if (tmp<ans) ans=tmp;
	}
	return ans;
}

int i;
int main()
{
	scanf("%d",&n);
	for (i=1;i<=n;i++) scanf("%d",&a[i]);
	cout<<calc(1,n);
	return 0; 
}