ccf压缩编码（石子排序，四边形优化）

#include <iostream>
#include <cstdio>
using namespace std; 
const int maxn = 1005;
const int INF = 0x3f3f3f3f;
int a[maxn];
int sum[maxn];
int dp[maxn][maxn];
int s[maxn][maxn];
int n;
void init()
{
	for(int i = 1;i<=n;i++)
	{
		dp[i][i] = 0;
		s[i][i] = i;
	}
	for(int i = 1;i<=n-1;i++)
	{
		dp[i][i+1] = sum[i+1]-sum[i-1];
		s[i][i+1] = i;
	}
}
void solve()
{
	for(int r = 2;r<=n-1;r++)
	{
		for(int i = 1;i+r<=n;i++)
		{
			int j = i+r;
			dp[i][j] = INF;
			for(int k=s[i][j-1];k<=s[i+1][j];k++)
			{
				if(dp[i][j]>dp[i][k]+dp[k+1][j])
				{
					dp[i][j] = dp[i][k]+dp[k+1][j];
					s[i][j] = k;
				}
			}
			dp[i][j]+=(sum[j]-sum[i-1]);
		}
	}
}
int main() {
	scanf("%d",&n);
	sum[0] = 0;
	for(int i = 1;i<=n;i++)
	{
		scanf("%d",&a[i]);
		sum[i] = a[i]+sum[i-1];	
	}
	
	init();
	solve();
	cout<<dp[1][n]<<endl;
	
}