Lintcode-o (1) Check Power of 2

Using O (1) Time to check whether an integer n is a power of 2.

Example

For n=4, return True

For n=5, return false

Challenge

O (1) Time

Analysis:

Use bit manipulation. Be carefull is about the 0 and negtive integer.

Solution:

1 classSolution {2     /*3 * @param n:an integer4 * @return: True or False5      */6      Public BooleanCHECKPOWEROF2 (intN) {7         if(n<=0)return false;8         Booleanres = ((N & (n-1)) ==0)?true:false;9         returnRes;Ten     } One};

Lintcode-o (1) Check Power of 2