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. ~~~ public class Solution { public boolean isUgly(int num) { if(num<=0) return false; if(num==1) return true; while(num>=2 && num%2==0) num/=2; while(num>=3 && num%3==0) num/=3; while(num>=5 && num%5==0) num/=5; return num==1; } } “/=”屬于復合賦值運算符中的一種，表示把左邊的變量除于右邊變量的值賦予右邊的變量，例如：a/=b等價于a=a/b。同類的還有=（例如：a=b等價于a=a*b）、+=(例如：a+=b等價于a=a+b)、-=（例如：a-=b等價于a=a-b）、%=（例如：a%=b等價于a=a%b（這里的%符號是求余運算符，a%b表示求a除于b的余數））。或許你還會問為什么a/=b為什么不直接用a=a/b來表示，這是因為這樣的表示方法可以讓程序更加簡潔。 ~~~