HDU 1479（Numbers That Count）

模拟题，由于最大模拟次数较小，所以每次计算出全部结果，再进行比较。

#include <cstdio>
#include <cstring>
const int MAXN = 85;

int num[10];
char s[16][MAXN];

int main()
{
    while (scanf("%s", s[0]))
    {
        if (s[0][0] == '-')
            break;

        for (int i = 1; i <= 15; i++) //计算15次操作的所有结果
        {
            memset(num, 0, sizeof(num));
            for (int j = 0; j < MAXN && s[i - 1][j]; j++)
            {
                num[s[i - 1][j] - '0']++;
            }
            int index = 0;
            for (int j = 0; j < 10; j++)
            {
                if (num[j] != 0)
                {
                    if (num[j] > 9)
                        s[i][index++] = num[j] / 10 + '0';
                    s[i][index++] = num[j] % 10 + '0';

                    s[i][index++] = j + '0';
                }
            }
            s[i][index] = '\0';
        }

        if (strcmp(s[0], s[1]) == 0)
        {
            printf("%s is self-inventorying\n", s[0]);
            continue;
        }

        if (strcmp(s[15], s[14]) == 0)
        {
            int i;
            for (i = 13; i >= 0; i--)
            {
                if (strcmp(s[15], s[i]) != 0) 
                    break;
            }
            printf("%s is self-inventorying after %d steps\n", s[0], i + 1);
            continue;
        }

        bool flag = false;
        for (int i = 0; i < 15 && !flag; i++)
        {
            for (int j = i + 1; j < 16; j++)
            {
                if (strcmp(s[i], s[j]) == 0)
                {
                    printf("%s enters an inventory loop of length %d\n", s[0], j - i);
                    flag = true;
                    break;
                }
            }
        }
        if (flag == false)
            printf("%s can not be classified after 15 iterations\n", s[0]);
    }
    return 0;
}

继续加油。