leetcode263题 题解 翻译 C语言版 Python版

263. 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

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.

263.丑数

写一个程序来检查一个给定的数是不是一个丑陋的数。

丑陋的数是指那些质因子只包括2，3，5的正整数。比如说：6，8是丑数，但14不是丑数因为它有一个质因子7.

注意1比较特殊，我们把他看作丑数。

思路：给定一个数后，我们只需要将其每次除2或除3或除5，如果三个同时除不通就说明有其他质因子，只要有一个能除通就继续下一轮。注意特殊情况的单独处理。

bool isUgly(int num) {
if (num <= 0) return false;
if (num == 1) return true;
while (num > 1){
int flag = 0;
if (num % 2 != 0){
flag++;
}
else{
num /= 2;
continue;
}
if (num % 3 != 0){
flag++;
}
else{
num /= 3;
continue;
}
if (num %5 != 0){
flag++;
}
else {
num /= 5;
continue;
}
if (flag == 3) return false;
}
return true;
}

class Solution(object):
def isUgly(self, num):
"""
:type num: int
:rtype: bool
"""
if num <= 0: return False
if num == 1: return True
while num > 1:
flag = 0
if num % 2 != 0:
flag += 1
else:
num /= 2
continue
if num % 3 != 0:
flag += 1
else:
num /= 3
continue
if num % 5 != 0:
flag += 1
else:
num /= 5
continue
if flag == 3: return False
return True