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Write a program to check whether a given number is an ugly number`.
Ugly numbers are positive numbers whose prime factors only include 2, 3, 5. For example, 6, 8 are ugly while 14 is not ugly since it includes another prime factor 7.
Note that 1 is typically treated as an ugly number.
Given num = 8 return true
Given num = 14 return false
解题
直接递归
public class Solution { /** * @param num an integer * @return true if num is an ugly number or false */ public boolean isUgly(int num) { // Write your code here if(num <=0) return false; if(num == 1) return true; if(num %2 ==0) return isUgly(num/2); if(num %3 ==0) return isUgly(num/3); if(num%5 ==0) return isUgly(num/5); return false; } }
while 循环‘
public class Solution { /** * @param num an integer * @return true if num is an ugly number or false */ public boolean isUgly(int num) { // Write your code here if(num <=0) return false; while(num %2 ==0) num/=2; while(num %3 ==0) num/=3; while(num%5 ==0) num/=5; return num==1; } }
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原文地址：http://www.cnblogs.com/theskulls/p/5377355.html
