样例也过不了，不知道什么错，请各位大佬赐教QAQ

代码：

#include<bits/stdc++.h>
using namespace std;
int n,a[305],f[305][305],sum[305];
int main(){
	cin >> n;
	memset(f,0x3f,sizeof(f));
	for(int i = 1;i <= n;i++){
		cin >> a[i];
		sum[i] = sum[i-1]+a[i];
	}
	for(int i = 1;i <= n;i++){
		f[i][i] = 0;
	}
	for(int len = 2;len <= n;len++){
		for(int i = 1;i <= n-len+1;i++){
			int j=i+len-1;
			for(int k = i;k < j;k++){
				f[i][j]=min(f[i][j],f[i][k]+f[k+1][j]+sum[j]-sum[i-1]);
			}
		}
	}
	cout << f[1][n] << endl;
	memset(f,0x3f,sizeof(f));
	for(int i = 1;i <= n;i++){
		f[i][i] = 0;
	}
	for(int len = 2;len <= n;len++){
		for(int i = 1;i <= n-len+1;i++){
			int j=i+len-1;
			for(int k = i;k < j;k++){
				f[i][j]=max(f[i][j],f[i][k]+f[k+1][j]+sum[j]-sum[i-1]);
			}
		}
	}
	cout << f[1][n];
	return 0;
}