2^x mod n = 1（hd1395）

2^x mod n = 1

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 14214    Accepted Submission(s):
4403

Problem Description

Give a number n, find the minimum x(x>0) that
satisfies 2^x mod n = 1.

 

Input

One positive integer on each line, the value of
n.

 

Output

If the minimum x exists, print a line with 2^x mod n =
1.

Print 2^? mod n = 1 otherwise.

You should replace x and n with
specific numbers.

 

Sample Input

2

5

 

Sample Output

2^? mod 2 = 1

2^4 mod 5 = 1

 #include <iostream>
 using namespace std;
 int main()
 {
     int n,i,j;
     while(cin>>n)
     {
         int x=;
         if(n==||n%==)
         {
             cout<<"2^? mod "<<n<<" = 1\n";
             continue;
         }
         for(i=;;i++)
         {
             if(x==)
                 break;
             else
             {
                 x=x*;
                 x=x%n;
             }
         }
         cout<<"2^"<<i+<<" mod "<<n<<" = 1"<<endl;
     }
 }