hihocoder #1338 : A Game（区间dp）

 1 #define bug(x) cout<<#x<<" is "<<x<<endl
 2 #define IO std::ios::sync_with_stdio(0)
 3 #include <bits/stdc++.h>
 4 #define iter ::iterator
 5 #define pa pair<int,int>
 6 #define pp pair<int,pa>
 7 using namespace  std;
 8 #define ll long long
 9 #define mk make_pair
10 #define pb push_back
11 #define se second
12 #define fi first
13 #define ls o<<1
14 #define rs o<<1|1
15 const ll mod=1e9+7;
16 const int N=1e3+10;
17 
18 int a[N],b[N];
19 int d[N][N];
20 
21 int n;
22 
23 int dfs(int l,int r){
24     if(l==r)return a[l];
25 
26     if(d[l][r])return d[l][r];
27 
28     int ans=-1e9;
29 
30     ans=max(ans,b[r]-b[l-1]-dfs(l+1,r));
31     ans=max(ans,b[r]-b[l-1]-dfs(l,r-1));
32     return d[l][r]=ans;
33 }
34 int main(){
35 
36     scanf("%d",&n);
37     for(int i=1;i<=n;i++){
38         scanf("%d",&a[i]);
39         b[i]=b[i-1]+a[i];
40     }
41     printf("%d\n",dfs(1,n));
42 
43 }

 1 #define bug(x) cout<<#x<<" is "<<x<<endl
 2 #define IO std::ios::sync_with_stdio(0)
 3 #include <bits/stdc++.h>
 4 #define iter ::iterator
 5 #define pa pair<int,int>
 6 #define pp pair<int,pa>
 7 using namespace  std;
 8 #define ll long long
 9 #define mk make_pair
10 #define pb push_back
11 #define se second
12 #define fi first
13 #define ls o<<1
14 #define rs o<<1|1
15 const ll mod=1e9+7;
16 const int N=1e3+10;
17 
18 int n;
19 int a[N],b[N];
20 int d[N][N];
21 int main(){
22     scanf("%d",&n);
23     for(int i=1;i<=n;i++){
24         scanf("%d",&a[i]);
25         b[i]=b[i-1]+a[i];
26         d[i][1]=a[i];
27     }
28     for(int j=2;j<=n;j++){
29         for(int i=1;i<=n;i++){
30             d[i][j]=max(b[i+j-1]-b[i-1]-d[i][j-1],b[i+j-1]-b[i-1]-d[i+1][j-1]);
31         }
32     }
33     printf("%d\n",d[1][n]);
34 }