LeetCode#202 Happy Number

Problem Definition:

Write an algorithm to determine if a number is "happy".

A happy number is a number defined by the following process: Starting with any positive integer, replace the number by the sum of the squares of its digits, and repeat the process until the number equals 1 (where it will stay), or it loops endlessly in a cycle which does not include 1. Those numbers for which this process ends in 1 are happy numbers.

Example: 19 is a happy number

• 1² + 9² = 82
• 8² + 2² = 68
• 6² + 8² = 100
• 1² + 0² + 0² = 1

Solution:

 1 def isHappy(self,n):
 2         d={}             #用字典来存储n
 3         while True:
 4             if n==1:    #一旦某个平方和为1，则肯定happy
 5                 return True
 6             if n not in d:
 7                 d[n]=0  #0只是一个标记
 8                 n=self.getSum(n)
 9             else:         #出现重复且不是1的平方和，不happy
10                 return False
11 def getSum(self,n):
12         s=0
13         while n!=0:
14             a=n%10
15             n=n/10
16             s+=a**2
17         return s

原文：http://www.cnblogs.com/acetseng/p/4654802.html