区间（环形）dp

 1 #include <iostream>
 2
 3 using namespace std;
 4
 5 const int MAXN=110;
 6
 7 int n;
 8 int a[MAXN*2];
 9 int dp[MAXN*2][MAXN*2];
10
11 int main()
12 {
13     cin>>n;
14     for (int i=1;i<=n;i++)
15     {
16         cin>>a[i];
17         a[i+n]=a[i];
18     }
19
20     for (int len=2;len<=n;len++)   //枚举合并长度
21     {
22         for (int i=1;i+len-1<=2*n;i++)   //枚举左端点
23         {
24             int j=i+len-1;   //右端点
25             for (int k=i;k<=j-1;k++)   //枚举间断点
26             {
27                 dp[i][j]=max(dp[i][j],dp[i][k]+dp[k+1][j]+a[i]*a[k+1]*a[j+1]);
28             }
29         }
30     }
31
32     int ans=0;
33     for (int i=1;i<=n;i++)
34     {
35         ans=max(ans,dp[i][i+n-1]);
36     }
37     cout<<ans<<endl;
38
39     return 0;
40 }