问题描述:
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.
注意考虑循环退出条件以及边界条件。
代码:
class Solution {
public:
bool isUgly(int num) {
if(num <= 0)
{
return false;
}
if(num == 1)
{
return true;
}
while(num)
{
if(num % 2 == 0)
{
num /= 2;
}
else if(num % 3 == 0)
{
num /= 3;
}
else if(num % 5 == 0)
{
num /= 5;
}
else
{
return false;
}
if(num == 1)
{
return true;
}
}
}
};