Power of leetcode-4 - simple

title ：342 4 The power of - Simple

subject

Given an integer , Write a function to determine if it is 4 Power square . If it is , return true ; otherwise , return false .

Integers n yes 4 To the power of ： There are integers x bring n == 4x

Example 1

 Input ：n = 16
 Output ：true

Example 2

 Input ：n = 5
 Output ：false

Example 3

 Input ：n = 1
 Output ：true

Tips

• -231 <= n <= 231 - 1

Code Java

public boolean isPowerOfFour(int n) {
    
    if (n == 1 || n == 4)
        return true;
    if (n < 4)
        return false;
    int a = (n - 1) & n; //  Determine whether it is 2 The power of 
    if (a == 0){
    
        if (Math.sqrt(n) % 4 == 0)  //  yes 2 The power of ,4^x  The prescription is  2^x
            return true;
        else
            return false;
    }
    else
        return false;
}