白书 7.1.2最大连续乘积

代码如下：

#include<cstdio>
#include<cstring>
int s[20];
long long int cal(int b, int e)
{
    long long int sum = 1;
    for(;b <= e; b++)
    {
        sum *= s[b];
    }
    return sum;
}
int main()
{
    freopen("text.txt", "r", stdin);
    int n;
    while(scanf("%d", &n) != EOF)
    {
        long long int re = 1;
        memset(s, 0, sizeof(s));
        for(int i = 0; i < n; i++)
        {
            scanf("%d", s+i);
        }
        for(int be = 0; be < n; be++)
            for(int ed = be; ed < n; ed++)
            {
                re = cal(be, ed)>re?cal(be,ed):re;
            }
        if(re < 0) puts("-1");
        else
            printf("%lld\n", re);
    }
}