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package com.xiaobu.leetcode;/** * @author xiaobu * @version JDK1.8.0_171 * @date on  2019/10/23 16:51 * @description 判断一个整数是否为3的次幂 还可以用循环、递归实现 */public class CheckPowerOfThree {
       public static boolean checkIsPowerOfThreeByEazyWay(int n) {
           return n > 0 && Math.pow(3, 19) % n == 0;    }    public static void main(String[] args) {
           boolean flag = checkIsPowerOfThreeByEazyWay(1);        System.out.println("flag = " + flag);        System.out.println("Integer.MAX_VALUE="+Integer.MAX_VALUE);        //3的20次幂        long threePowOfNineteen = (long) Math.pow(3, 19);        System.out.println("threePowOfNineteen = " + threePowOfNineteen);        long threePowOfTwenty = (long) Math.pow(3, 20);        System.out.println("threePowOfTwenty = " + threePowOfTwenty);        boolean result = checkIsPowerOfThreeByRecursive(81);        System.out.println("result = " + result);    }    /**     * 递归法     */    public static boolean checkIsPowerOfThreeByRecursive(int n) {
           if (n == 1) {
               return true;        }        if (n == 0) {
               return false;        }        return checkIsPowerOfThreeByRecursive(n / 3) && n % 3 == 0;    }}

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