1489.cpp

2^x mod n = 1 acm竞赛题 Give a number n, find the minimum x that satisfies 2^x mod n = 1. Input

#include<iostream>
using namespace std;
int main()
{
    int n,t,i,able;
    while(cin>>n)
    {

        i=1;
        if(n%2==0||n<2)cout<<"2^? mod "<<n<<" = 1"<<endl;
        else
        {
            able=1;
            t=2;
            while(1)
            {
                while(t>n)t-=n;
                if(t%n==1){cout<<"2^"<<able<<" mod "<<n<<" = 1"<<endl;break;}
                ++able;
                t=t*2;
            }

        }
    }
}