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  • lintcode:Ugly Number I

    Ugly Number

    Write a program to check whether a given number is an ugly number`.

    Ugly numbers are positive numbers whose prime factors only include 235. For example, 68 are ugly while 14 is not ugly since it includes another prime factor 7.

     注意事项

    Note that 1 is typically treated as an ugly number.

    样例

    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:https://www.cnblogs.com/bbbblog/p/5377355.html
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