O - Treats for the Cows 区间DP

#include <stdio.h>
#include <string.h>
#include <algorithm>
using namespace std;

#define MAXN 2002
/*
区间DP,从后向前推，dp[i][j]表示首端元素为a[i],尾端为a[j]的情况
    dp[i][j] = max(dp[i+1][j]+t*a[i],dp[i][j-1]+t*a[j])
*/
int a[MAXN],dp[MAXN][MAXN];
int main()
{
    int n;
    scanf("%d",&n);
    for(int i=1;i<=n;i++)
        scanf("%d",&a[i]);
    for(int i=1;i<=n;i++)
        dp[i][i] = n*a[i];//最后一个卖出元素是a[i]的情况
    for(int l=1;l<n;l++)
    {
        for(int i=1;i+l<=n;i++)
        {
            int j = i+l;
            dp[i][j] = max(dp[i+1][j]+(n-l)*a[i],dp[i][j-1]+(n-l)*a[j]);
        }
    }
    printf("%d\n",dp[1][n]);
    return 0;
}