# [LeetCode]#202. Happy Number

Environment: Python 3.7

Key technique: Divide-and-conquer algorithm

**Example:**

**Input:** 19

**Output:** true

**Explanation: **

12 + 92 = 82

82 + 22 = 68

62 + 82 = 100

12 + 02 + 02 = 1

**Analysis: There are two functions in the code. One is for computing square sum, and another is for judging Happy number or not.**

**Solution:**

`class Solution:`

def Sum(self,num):

str_num=str(num)

res=0

for i in str_num:

res+=(int(i)**2)

return res

def isHappy(self, n: int) -> bool:

Table=[]

while n not in Table:

Table.append(n)

n=self.Sum(n)

if(n==1):

return True

break

if n in Table:

return False

**Submitted result:**

**lesson learn:**

We can use ‘self.’ for using another function.

**Reference:**

https://leetcode.com/problems/happy-number/discuss/538336/Python-Easy