[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