LeetCode:Power of Two

Power of Two

Total Accepted: 38815  Total Submissions: 118702  Difficulty: Easy

Given an integer, write a function to determine if it is a power of two.

Credits:
Special thanks to @jianchao.li.fighter for adding this problem and creating all test cases.

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  Math Bit Manipulation

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思路：

1.n中的二进制表示中只有一个1的符合；

2.令x = (n & n-1)，由x是n去掉最后一个1的数，求法参考博文【23个位运算技巧】。

class Solution {
public:
    bool isPowerOfTwo(int n) {
        return n>0 && !(n & (n-1));  // n&(n-1)去掉最后一个1
    }
};