HDU 1212 大整数的取模运算

#include <cstdio>
#include <cstring>
#include <iostream>
using namespace std;
#define ll long long
int b;
char s[1005];

int main()
{
  //  freopen("a.in" , "r" , stdin);
    while(~scanf("%s%d" , s , &b))
    {
        int len = strlen(s);
        int p = len-1 , t = 0; //t表示后面要乘几次100000
        int cur = 0 ;
        while(p >= 0){
            ll num = 0 , mul = 1 ;
            for(int i = 0 ; i<5&&p>=0 ; i++){
                num += mul * (s[p] - ‘0‘);
                mul *= 10;
                p--;
            }
          //  cout<<"num: "<<num<<endl;
            num = num % b;
            for(int i = 1 ; i<=t ; i++){
                num *= 100000;
                num %= b;
            }
            num += cur;
            num %= b;
            cur = num;
            t++;
        }
        printf("%d\n" , cur);
    }
    return 0;
}