poj 1250 Tanning Salon

#include<iostream>#include<stdio.h>#include<string.h>using namespace std;const int MAX = 60;int main(){    int n, i, id, ans;    char str[MAX];    bool vis[MAX], tan[MAX];    while(cin >> n && n){        memset(vis, 0, sizeof(vis));        memset(tan, 0, sizeof(tan));        cin >> str;        ans = 0;        for(i = 0; i < strlen(str); i ++){ id = str[i] - 'A'; if(!vis[id]){     vis[id] = true;     if(n > 0){         n --;         tan[id] = true;     }else ans ++; }else{     if(tan[id]) n ++; }        }        if(ans == 0)printf("All customers tanned successfully.n");        else printf("%d customer(s) walked away.n", ans);    }    return 0;}