poj3661

dp

f[i] = max(f[i], sum(i~i+j-1) + f[i + j * 2]) 或者 f[i] = f[i + 1]

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
using namespace std;

#define maxn 10005

int n, m;
int dis[maxn];
int f[maxn];
int sum[maxn];

void input()
{
    scanf("%d%d", &n, &m);
    for (int i = 1; i <= n; i++)
        scanf("%d", &dis[i]);
    sum[0] = dis[0] = 0;
    for (int i = 1; i <= n; i++)
        sum[i] = sum[i - 1] + dis[i];
}

void work()
{
    f[n + 1] = 0;
    for (int i = n; i >= 1; i--)
    {
        f[i] = f[i + 1];
        for (int j = 1; j <= m && i + j * 2 <= n + 1; j++)
            f[i] = max(f[i], sum[i + j - 1] - sum[i - 1] + f[i + j * 2]);
    }
    printf("%d\n", f[1]);
}

int main()
{
    //freopen("t.txt", "r", stdin);
    input();
    work();
    return 0;
}