n的幂

//2的幂
public class Solution {
    public boolean isPowerOfFour(int num) {
        if(num>1){
            while(num%2==0)
                num/=2;
        }
        return num==1;
    }
}
//3的幂
public class Solution {
    public boolean isPowerOfFour(int num) {
        if(num>1){
            while(num%3==0)
                num/=3;
        }
        return num==1;
    }
}
//4的幂
public class Solution {
    public boolean isPowerOfFour(int num) {
        if(num>1){
            while(num%4==0)
                num/=4;
        }
        return num==1;
    }
}