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PowerOfTwo.java
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44 lines (41 loc) · 915 Bytes
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package ds;
/**
* 2的幂
* <p>
* 给定一个整数，编写一个函数来判断它是否是 2 的幂次方。
* <p>
* 示例 1:
* <p>
* 输入: 1
* 输出: true
* 解释: 20 = 1
* 示例 2:
* <p>
* 输入: 16
* 输出: true
* 解释: 24 = 16
* 示例 3:
* <p>
* 输入: 218
* 输出: false
*
* @author yangyi 2019年02月01日18:04:15
*/
public class PowerOfTwo {
public boolean isPowerOfTwo(int n) {
boolean isPowerOfTwo = false;
if (n < 0) {
return false;
}
if (n != 0) {
isPowerOfTwo = (n & (n - 1)) == 0;
}
return isPowerOfTwo;
}
public static void main(String[] args) {
PowerOfTwo powerOfTwo = new PowerOfTwo();
System.out.println(powerOfTwo.isPowerOfTwo(1));
System.out.println(powerOfTwo.isPowerOfTwo(16));
System.out.println(powerOfTwo.isPowerOfTwo(218));
}
}