brbustoj 1818 石子合并问题--直线版

比较经典且基础的区间dp,转移方程为

dp_max[i][j] = max(dp_max[i][j],dp_max[i][k] + dp_max[k+1][j] + sum[j]-sum[i-1]);
dp_min[i][j] = min(dp_min[i][j],dp_min[i][k] + dp_min[k+1][j] + sum[j]-sum[i-1]);

#include <fstream>
#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
using namespace std;
int main()

{
    int n,a[],sum[];
    int dp_max[][];
    int dp_min[][];
    while(~scanf("%d",&n))
    {
        memset(dp_min,0x3f,sizeof(dp_min));
        memset(dp_max,,sizeof(dp_max));
        sum[] = ;
        for(int i = ;i <= n;i++)
        {
            dp_max[i][i] = dp_min[i][i] = ;
            scanf("%d",&a[i]);
            sum[i] = sum[i-] + a[i];
        }
        for(int len = ;len < n;len++)
        {
            for(int i = ;i <= n-len;i++)
            {
                int j = i + len;
                for(int k = i;k < j;k++)
                {
                    dp_max[i][j] = max(dp_max[i][j],dp_max[i][k] + dp_max[k+][j] + sum[j]-sum[i-]);
                    dp_min[i][j] = min(dp_min[i][j],dp_min[i][k] + dp_min[k+][j] + sum[j]-sum[i-]);
                }
            }
        }
        printf("%d %d\n",dp_min[][n],dp_max[][n]);
    }
    return ;
}