Description
Write an algorithm to determine if a number n 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.
- 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.
Return true if n is a happy number, and false if not.
Example 1:
Input: n = 19 Output: true Explanation: 12 + 92 = 82 82 + 22 = 68 62 + 82 = 100 12 + 02 + 02 = 1
Example 2:
Input: n = 2 Output: false
Constraints:
1 <= n <= 231 - 1
Solution
Python3
class Solution:
def isHappy(self, n: int) -> bool:
seen = set()
while n != 1 and n not in seen:
seen.add(n)
curr = 0
while n > 0:
a, b = divmod(n, 10)
curr += b * b
n = a
n = curr
return n == 1