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  • LeetCode 342. Power of Four

    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?

    先说明用循环:

    如下

    class Solution {
    public:
        bool isPowerOfFour(int num) {
            if(num<1)return false;
            char position=-1;
            int i=0;
            while(i<=31)
            {
                if(num&(1<<(i)))
                {
                    if(-1!=position&&position!=i)
                    return false;
                    position=i;
                }
                ++i;
            }
            if(position%2)return false;
            else return true;
        }
    };

    然后我发现题目中提示,你可以不用循环或者递归吗?我就去搜寻了一下这个题目发现http://www.cnblogs.com/grandyang/p/5403783.html

    发现第三种方法很巧妙

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  • 原文地址:https://www.cnblogs.com/csudanli/p/5890604.html
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