hdu4283You Are the One (区间DP)

　　The TV shows such as You Are the One has been very popular. In order to meet the need of boys who are still single, TJUT hold the show itself. The show is hold in the Small hall, so it attract a lot of boys and girls. Now there are n boys enrolling in. At the beginning, the n boys stand in a row and go to the stage one by one. However, the director suddenly knows that very boy has a value of diaosi D, if the boy is k-th one go to the stage, the unhappiness of him will be (k-1)*D, because he has to wait for (k-1) people. Luckily, there is a dark room in the Small hall, so the director can put the boy into the dark room temporarily and let the boys behind his go to stage before him. For the dark room is very narrow, the boy who first get into dark room has to leave last. The director wants to change the order of boys by the dark room, so the summary of unhappiness will be least. Can you help him?

　　The first line contains a single integer T, the number of test cases. For each case, the first line is n (0 < n <= 100)
　　The next n line are n integer D1-Dn means the value of diaosi of boys (0 <= Di <= 100)

　　For each test case, output the least summary of unhappiness .

2
　　
5
1
2
3
4
5

5
5
4
3
2
2

Case #1: 20
Case #2: 24
题意：有n个人排成一纵队，每个人都有一个不高兴值D，从第一个出去登场或进入黑屋（先进后出，可以等待也可以出去），第k个等待的人不高兴值变成（k-1）*D.
#include<stdio.h>
__int64 min(__int64 a,__int64 b)
{
    return a>b?b:a;
}
int main()
{
    int n,t,c=0;
    __int64 dp[105][105],a[105],ans[105];
    scanf("%d",&t);
    while(t--)
    {
        scanf("%d",&n); ans[0]=0;
        for(int i=1;i<=n;i++)
        {
            scanf("%I64d",&a[i]);
            ans[i]=ans[i-1]+a[i];
            for(int j=1;j<=n; j++)
            dp[i][j]=0;
        }
        for(int r=1;r<n;r++)
        for(int i=1;i<=n-r;i++)
        {
            int j=i+r;
            dp[i][j]=ans[j]-ans[i]+dp[i+1][j];//在区间里第一个出的情况
            for(int k=i+1;k<=j;k++)
            {
                dp[i][j]=min(dp[i][j],a[i]*(k-i)+dp[i+1][k]+(ans[j]-ans[k])*(k-i+1)+dp[k+1][j]);
            }
        }
        printf("Case #%d: %I64d\n",++c,dp[1][n]);
    }
}