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Leetcode 231 Power Of Two

发表于 更新于 分类于 Valine：
本文字数： 583 阅读时长 ≈ 1 分钟

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

Example 1:

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Input: n = 1
Output: true
Explanation: 20 = 1

Example 2:

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Input: n = 16
Output: true
Explanation: 24 = 16

Example 3:

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Input: n = 3
Output: false

Example 4:

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Input: n = 4
Output: true

Example 5:

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Input: n = 5
Output: false

Constraints:

  • -231 <= n <= 231 - 1

位运算

直接判断二进制的n 是不是 开头一个1, 后面n个0的形式

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class Solution {
    public boolean isPowerOfTwo(int n) {
        if(n <= 0)
            return false;
        while(n != 1)
        {
            if((n & 1) == 0)
            {
                n = n >>> 1;
            }
            else
            {
                if(n != 1)
                    return false;
            }
        }
        return true;
    }
}