Monkey Party HDU 3506 区间dp

#include<iostream>
#include<algorithm>
#include<cstring>
#include<stack>
#include<cmath>
#include<queue>
using namespace std;
#define ll long long
#define N 2005
#define rep(i,l,r) for(i=l;i<=r;i++)
const int mod = 1e9 + 7;
const int INF = 0x3f3f3f3f;
#define eps 0.00000001//偏差值1e8
#define pi acos(-1.0)//高精度圆周率
const int maxp = 1010;                    //点的数量
int a[N];
int dp[N][N];
int sum[N];
int s[N][N];
int main()
{
    int i, j, k;
    int n, ret = 0, m, maxn = 0, count = 0;
    int t, x, len;
    while (cin >> n) {
        sum[0] = 0;
        memset(dp, INF, sizeof(dp));
        rep(i, 1, n)
        {
            cin >> a[i];
            sum[i] = sum[i - 1] + a[i];
            dp[i][i] = 0;
            s[i][i] = i;
        }
        rep(i, 1, n)
        {
            sum[i + n] = sum[i + n - 1] + a[i];
            s[i + n][i + n] = i + n;
            dp[i + n][i + n] = 0;
        }
        rep(len, 2, n)
        {
            rep(i, 1, 2 * n - 1)
            {
                j = i + len - 1;
                if (j > 2 * n - 1)break;
                rep(k, s[i][j - 1], s[i + 1][j])
                {
                    if (dp[i][k] + dp[k + 1][j] + sum[j] - sum[i - 1] < dp[i][j])
                    {
                        dp[i][j] = dp[i][k] + dp[k + 1][j] + sum[j] - sum[i - 1];
                        s[i][j] = k;
                    }
                }
            }
        }
        int ans = INF;
        rep(i, 1, n)
        {
            ans = min(ans, dp[i][i + n - 1]);
        }
        cout << ans << endl;
    }
    return 0;
}