Happy Number

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题目：

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

解题思路：

本题比较简单，题目要求对任意一个正整数，不断各个数位上数字的平方和，若最终收敛为1，则该数字为happy number，否则程序可能从某个数开始陷入循环。这道题目我们只用根据规则进行计算，并使用一个哈希表存储已经出现过的数字即可。

class Solution:
# @param {integer} n
# @return {boolean}
def isHappy(self, n):
dic = {}
while n not in dic.keys():
if n==1:
return True
dic[n], tmp = 1, 0
for i in str(n):
tmp += int(i)*int(i)
n = tmp
return False

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