Interview Question for Software Engineer Test at Google:

2a.

Simple solution:

boolean isPowerOfTwo(int n){
    double d = (Math.log(n))/(Math.log(2)); // == log(base 2) n
    if (d == Math.floor(d)) return true;
    return false;
}

Without Java Math class:

boolean isPowerOfTwo(int n){
    int x = 1;
    while(true){
           if (x == n) return true;
           if (x > n) return false;
           x = x * 2;
      }
}

or

boolean isPowerOfTwo(int n){
    if (n < 1) return false;
    while(n != 1){
        if (n % 2 != 0) return false;
        n = n/2;
    }
    return true;
}

Are there any problems with these approaches? What might be a better approach?

boolean isPowerOfTwo (int a) {
 return (a&(a-1)==0);
}

@ellemeno:
You are expected to give the solution as Anonymous

which by the way can be done in java as well , ( it's generally called bit wise operations)

@ellemeno:
You are expected to give the solution as Anonymous

which by the way can be done in java as well , ( it's generally called bit wise operations)