HEU 5019 Max

/**//**************************************
Problem: HEU 5019 Max
Time: 0.0030 s
Memory: 552 k 
Accepted Time: 2009-04-28 11:46:04
Tips: 因为有负数，所以要考虑最小值 
**************************************/
#include <stdio.h>
char b[110];
long max[110][110],min[110][110];
long fun(int a1,int a2,int a3,int a4,int flag)
{
    long sum;
    switch(flag)
    {
        case 1:
            if(b[a2]=='+')sum=max[a1][a2]+max[a3][a4];
            else sum=max[a1][a2]*max[a3][a4];
            break;
        case 2:
            if(b[a2]=='+')sum=min[a1][a2]+min[a3][a4];
            else sum=min[a1][a2]*min[a3][a4];
            break;
        case 3:
            if(b[a2]=='+')sum=min[a1][a2]+max[a3][a4];
            else sum=min[a1][a2]*max[a3][a4];
            break;
        case 4:
            if(b[a2]=='+')sum=max[a1][a2]+min[a3][a4];
            else sum=max[a1][a2]*min[a3][a4];
            break;        
    }
    return sum;
}
int main()
{
    int n;
    while(scanf("%d",&n)!=EOF)
    {
        int i,j,k,t;
        for(i=1;i<=n;i++)
        {
            scanf("%ld",&max[i][i]);
            min[i][i]=max[i][i];
            if(i!=n)scanf("%s",&b[i]);
        }
        long temp;
        for(i=n-1;i>=1;i--)
        {
            for(j=1;j<=i;j++)
            {
                long max1=-100000000;
                long min1=100000000;
                for(k=j;k<j+n-i;k++)
                {
                    for(t=1;t<5;t++)
                    {
                        temp=fun(j,k,k+1,j+n-i,t);
                        if(temp>max1)max1=temp;
                        if(temp<min1)min1=temp;
                    }
                }
                max[j][j+n-i]=max1;
                min[j][j+n-i]=min1;    
            }
        }
        printf("%ld\n",max[1][n]);
    }
    return 0;
}