[leetcode]263. Ugly Number

题目

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.

代码

1.

public  boolean isUgly(int num) { if(num <= 0){ return false;} if(num == 1 || num == 2 || num == 3 || num == 5){return true;} while(num >= 2){ if(num % 2 !=0){ break; } else { num = num /2; } } if(num == 1){ return true; }else{ while(num >= 3){ if(num % 3 !=0){ break; }else{ num = num/3; }  } if(num ==1){ return true; }else{ while(num >=5){ if(num % 5 !=0){ break; }else{ num = num/5; } } } if(num == 1){ return true; }  } return false; }

2.

public  boolean isUgly(int num) {      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;            }