poj 3186 Treats for the Cows (区间dp)

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
const int maxn=2007;
int a[maxn],dp[maxn][maxn];

int main()
{
    int n;
    while(~scanf("%d",&n)){
        for(int i=1;i<=n;i++){
            scanf("%d",&a[i]);
        }
        memset(dp,0,sizeof(dp));
        for(int i=1;i<=n;i++){
            dp[i][i]=a[i];
        }
        for(int i=n;i>=1;i--){
            for(int j=i;j<=n;j++){
                dp[i][j]=max(dp[i+1][j]+a[i]*(n+i-j),dp[i][j-1]+a[j]*(n+i-j));
            }
        }
        printf("%d\n",dp[1][n]);
    }
    return 0;
}