poj3186

dp

f[i][j] = max(f[i + 1][j] + sum(i + 1,j) + v[i],f[i][j - 1] + sum(i,j - 1) + v[j])

View Code

#include <iostream>

#include <cstdio>

#include <cstdlib>

#include <cstring>

using namespace std;



#define maxn 2005



int n;

int v[maxn];

int f[maxn][maxn];

int sum[maxn];



void input()

{

    scanf("%d", &n);

    for (int i = 1; i <= n; i++)

        scanf("%d", &v[i]);

    v[0] = 0;

    sum[0] = v[0];

    for (int i = 1; i <= n; i++)

        sum[i] = sum[i - 1] + v[i];

}



int work()

{

    for (int i = 1; i <= n; i++)

        f[i][i] = v[i];

    for (int k = 1; k < n; k++)

    {

        for (int i = 1; i <= n - k; i++)

        {

            int j = i + k;

            f[i][j] = max(f[i + 1][j] + (sum[j] - sum[i]) + v[i],f[i][j - 1] + (sum[j - 1] - sum[i - 1]) + v[j]);

        }

    }

    return f[1][n];

}



int main()

{

//    freopen("t.txt", "r", stdin);

    input();

    printf("%d\n", work());

    return 0;

}