UVa 128 Software CRC

题意:

给一个字符串,每个字符占一个字节(即256进制数),在后面加两个字节,使得其模34943余数为0  

思路:

#include <cstdio>
#include <cstring>
#include <cstring>

const int MAXN = 1200;
int g = 34943;
char b[MAXN];
char s[32] = "0123456789ABCDEF";

int main()
{
    while (gets(b))
    {
        if (b[0] == '#')
            break;

        long long int k = 0, ans;
        for (int i = 0; b[i]; ++i)
            k = (k * 256 + b[i]) % g;
        ans = (g - (k<<16)%g) % g;

        int a[5];
        for (int i = 0; i < 4; ++i)
            a[i] = ans % 16, ans >>= 4;

        printf("%c%c %c%c\n", s[a[3]], s[a[2]], s[a[1]], s[a[0]]);
    }
    return 0;
}
posted @ 2012-12-02 22:28  kedebug  阅读(178)  评论(0编辑  收藏  举报