pipioj 1019: 堆石子（区间dp）

http://www.pipioj.online/problem.php?id=1019
 1 #define IO std::ios::sync_with_stdio(0);
 2 #define bug(x)  cout<<#x<<" is "<<x<<endl
 3 #include <bits/stdc++.h>
 4 #define iter ::iterator
 5 using namespace  std;
 6 typedef long long ll;
 7 typedef pair<int,int>P;
 8 #define pb push_back
 9 #define mk make_pair
10 #define se second
11 #define fi first
12 #define rs o*2+1
13 #define ls o*2
14 const ll mod=1e9+7;
15 const int N=1e3+5,M=3e6;
16 
17 
18 int d[N][N],a[N];
19 
20 int n;
21 int main(){
22 
23     while(~scanf("%d",&n)){
24         for(int i=1;i<=2*n-1;i++){
25             for(int j=i+1;j<=2*n;j++)d[i][j]=1e9;
26         }
27         for(int i=1;i<=n;i++){
28             scanf("%d",&a[i]);
29             a[i+n]=a[i];
30         }
31         for(int i=1;i<=2*n;i++){
32             a[i]+=a[i-1];
33         }
34         for(int l=n;l>=1;l--){
35             for(int r=l+1;r<=n;r++){
36                 for(int k=l;k<r;k++){
37                     d[l][r]=min(d[l][r],d[l][k]+d[k+1][r]+a[r]-a[l-1]);
38                 }
39             }
40         }
41         int ans=d[1][n];
42         printf("%d
",ans);
43     }
44     
45 }