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Day-2.py
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Day-2.py
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'''
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:
Input: 19
Output: true
Explanation:
12 + 92 = 82
82 + 22 = 68
62 + 82 = 100
12 + 02 + 02 = 1
'''
class Solution:
def isHappy(self, n: int) -> bool:
def next_num(num):
return sum(map(lambda x:int(x)**2, str(num)))
slow, fast = n, next_num(n)
while slow != fast and fast != 1:
slow = next_num(slow)
fast = next_num(next_num(fast))
return fast == 1 or not slow == fast