Uva 6173 B-Casting

题目链接：https://icpcarchive.ecs.baylor.edu/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=4184

求b进制下的a mod (b-1)的值。

(a*b^n)%(b-1) == a % (b-1)，很好推导。 

#include <iostream>#include <stdio.h>#include <string.h>#include <stdlib.h>using namespace std;#define Maxn 10000005int main(){#ifndef ONLINE_JUDGE    freopen("in.txt","r",stdin);#endif    int p;    int m,b;    int ans;    int len;    string str;    scanf(" %d",&p);    while(p--)    {        ans = 0;        scanf(" %d %d",&m,&b);        cin>>str;        len = str.length();        for(int i=0;i<len;i++)        {            ans += (str[i] - '0')%(b-1);            ans %= (b-1);        }        printf("%d %d\n",m,ans);    }    return 0;}