2952 细胞分裂 2

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<cmath>
 5 using namespace std;
 6 int n,m;
 7 int fastpow(int a,int b)
 8 {
 9     int r=1;
10     int base=a;
11     while(b!=0)
12     {
13         if(b%2==1)
14         r=(r*base)%m;
15         base=(base*base)%m;
16         b=b/2;
17     }
18     return r;
19 }
20 int main()
21 {
22     
23     scanf("%d%d",&n,&m);
24     //n=n-1;
25     cout<<fastpow(2,n)%m;
26     return 0;
27 }