LeetCode:Power of Four

原创于 2016-05-11 20:36:53 发布 · 3.2k 阅读

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本文提供了一个函数，用于判断给定的32位整数是否为4的幂次。通过位操作实现，避免了循环和递归。

Total Accepted: 12339 Total Submissions: 36888 Difficulty: Easy

Given an integer (signed 32 bits), write a function to check whether it is a power of 4.

Example:
Given num = 16, return true. Given num = 5, return false.

Follow up: Could you solve it without loops/recursion?

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

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c++ code:

class Solution {
public:
    bool isPowerOfFour(int num) {
        return num>0 && (num&(num-1))==0 && (num-1)%3==0;
    }
};