hdu 1024

参考了一下 http://moxi466839201.blog.163.com/blog/static/18003841620110220374942/

滚动数组   状态转移方程不太好理解 ....  f[i][j]=max(f[i][j-1],f[i-1][j-1])+a[j];

#include<cstdio>
#include<cstring>
#include<iostream>
#define maxn 1000010
#define INF 1000000000
using namespace std;

int dp[maxn],pre[maxn],a[maxn];
int main()
{
    int n,m,_max;
    while(scanf("%d%d",&m,&n) == 2)
    {
        memset(dp, 0, sizeof(dp));
        memset(pre, 0, sizeof(pre));
        for(int i = 1; i <= n; i++) scanf("%d",&a[i]);
        for(int i = 1; i <= m; i++)
        {
            _max = -INF;
            for(int j = i; j <= n; j++)
            {
                dp[j] = max(dp[j-1], pre[j-1])+a[j];
                pre[j-1] = _max;
                _max = max(_max, dp[j]);
            }
        }
        printf("%d\n",_max);
    }
    return 0;
}