poj1604

简单题

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

int lastdigit(char *buf)
{
    const int mod[20] =
    { 1, 1, 2, 6, 4, 2, 2, 4, 2, 8, 4, 4, 8, 4, 6, 8, 8, 6, 8, 2 };
    int len = strlen(buf), a[40], i, c, ret = 1;
    if (len == 1)
        return mod[buf[0] - '0'];
    for (i = 0; i < len; i++)
        a[i] = buf[len - 1 - i] - '0';
    for (; len; len -= !a[len - 1])
    {
        ret = ret * mod[a[1] % 2 * 10 + a[0]] % 5;
        for (c = 0, i = len - 1; i >= 0; i--)
            c = c * 10 + a[i], a[i] = c / 5, c %= 5;
    }
    return ret + ret % 2 * 5;
}

int main()
{
    //freopen("t.txt", "r", stdin);
    char st[10];
    while (scanf("%s", st) != EOF)
        printf("%5s -> %d\n", st, lastdigit(st));
    return 0;
}