POJ3186 Treats for the Cows —— 区间DP

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cmath>
 5 #include <algorithm>
 6 #include <vector>
 7 #include <queue>
 8 #include <stack>
 9 #include <map>
10 #include <string>
11 #include <set>
12 #define ms(a,b) memset((a),(b),sizeof((a)))
13 using namespace std;
14 typedef long long LL;
15 const double EPS = 1e-8;
16 const int INF = 2e9;
17 const LL LNF = 2e18;
18 const int MAXN = 2e3+10;
19 
20 int n;
21 int a[MAXN], dp[MAXN][MAXN];
22 
23 int main()
24 {
25     while(scanf("%d", &n)!=EOF)
26     {
27         for(int i = 1; i<=n; i++)
28             scanf("%d", &a[i]);
29 
30         for(int i = 1; i<=n; i++)
31             dp[i][i] = a[i]*n;
32 
33         for(int len = 2; len<=n; len++)
34         for(int i = 1; i+len-1<=n; i++)
35         {
36             int j = i+len-1;
37             dp[i][j] = max(dp[i+1][j]+(n-len+1)*a[i], dp[i][j-1]+(n-len+1)*a[j]);
38         }
39 
40         printf("%d\n", dp[1][n]);
41     }
42 }