poj1250

简单题

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
using namespace std;

#define maxl 60

int n;
char st[maxl];
bool have_bed[maxl];
bool occured[maxl];

int hash(char ch)
{
    return ch - 'A';
}

int work()
{
    int len = strlen(st);
    int ans = 0;
    for (int i = 0; i < len; i++)
        if (!occured[hash(st[i])])
        {
            occured[hash(st[i])] = true;
            if (n > 0)
            {
                have_bed[hash(st[i])] = true;
                n--;
            }else
                ans++;
        }else
        {
            if (have_bed[hash(st[i])])
            {
                have_bed[hash(st[i])] = false;
                n++;
            }
        }
        return ans;
}

int main()
{
    //freopen("t.txt", "r", stdin);
    while (scanf("%d", &n), n)
    {
        scanf("%s", st);
        memset(have_bed, 0, sizeof(have_bed));
        memset(occured, 0, sizeof(occured));
        int ans = work();
        if (ans == 0)
            puts("All customers tanned successfully.");
        else
            printf("%d customer(s) walked away.\n", ans);
    }
    return 0;
}