快速幂模板

快速幂模板

public class Main {
	public static long mulmod(long a,long b,long p) {
		long ans = 0,val = a;
		while(b!=0) {
			if(b%2==1) {
				ans+=val;
				ans%=p;
			}
			val*=2;
			val%=p;
			b/=2;
		}
		return ans;
	}
	public static long powmod(long a,long b,long p) {
		long ans = 0,val = a;
		while(b!=0) {
			if(b%2==1) {
				ans=mulmod(ans,val,p);
				ans%=p;
			}
			val=mulmod(val,val,p);
			val%=p;
			b/=2;
		}
		return ans;
	}
	public static void main(String[] args) {

	}
}