zoj 1926 Guessing Game

#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;

int main()
{
    int a[20],i,j,n,f;
    char s[100];
    memset(a,0,sizeof(a));
    f=1;
    while(~scanf("%d",&n))
    {
        if(n==0) break;
        gets(s);
        if(strcmp(s,"too high")==0)
        {
            for(i=n;i<=10;i++)
                {
                    if(a[i]==-1) f=0;
                    a[i]=1;
                }
        }
        else if(strcmp(s,"too low")==0)
        {
            for(i=1;i<=n;i++)
                {
                    if(a[i]==1) f=0;
                    a[i]=-1;
                }
        }
        else if(strcmp(s,"right on")==0)
        {
            if(a[n]!=0) f=0;
            if(f)
            //if(a[n]==0)
                printf("Stan may be honest
");
            else printf("Stan is dishonest
");
            memset(a,0,sizeof(a));
            f=1;
        }
    }
    return 0;
}