202 Happy Number
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
1^2 + 9^2 = 82
8^2 + 2^2 = 68
6^2 + 8^2 = 100
1^2 + 0^2 + 0^2 = 1
The Idea: Perform the sum of squares operation until either you trace back up, or 1 is reached. Complexity: ?
def getSquareDigitSum(self, num):
"""
:param num: int
:return: sum of squared digits
"""
return sum(int(i)**2 for i in str(num))
def isHappy(self, n):
"""
:param n: int
:return: bool
"""
visited = set()
cur_sum = self.getSquareDigitSum(n)
if cur_sum == 1:
return True
while not visited.__contains__(cur_sum):
visited.add(cur_sum)
cur_sum = self.getSquareDigitSum(cur_sum)
if cur_sum == 1:
return True
return False
Last modified 3yr ago