EOJ3134. 短信激活码（大数幂取模）

题面

输入只有5位，所以转化为long long类型用快速幂取模

前面补0的写法printf("%05lld ",ans);如果ans不足5位会在前面补0

#include<bits/stdc++.h>
using namespace std;
long long mod_exp(long long a, long long b, long long c)        //快速幂取余a^b%c
{
    long long res, t;
    res = 1 % c; 
    t = a % c;
    while (b)
    {
        if (b & 1)
        {
            res = res * t % c;
        }
        t = t * t % c;
        b >>= 1;
    }
    return res;
}
int main()
{
    int t;
    while(~scanf("%d",&t))
    {
        int cases=-1;
        while(t--)
        {
            cases++;
            char s[10],s2[10];
            scanf("%s",s);
            s2[0]=s[0];
            s2[1]=s[2];
            s2[2]=s[4];
            s2[3]=s[3];
            s2[4]=s[1];
            long long temp=(s2[0]-'1'+1)*10000+(s2[1]-'1'+1)*1000+(s2[2]-'1'+1)*100+(s2[3]-'1'+1)*10+(s2[4]-'1'+1)*1;
            printf("case #%d:
%05lld
",cases,mod_exp(temp,5,100000));
        }
    }
    return 0;
}