Leetcode - Happy Number Solution
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 in python
class Solution:
def isHappy(self, n: int) -> bool:
def digitSum(n):
return sum(map(lambda x:x*x, map(int,list(str(n)))))
seen = set()
while not n in seen:
seen.add(n)
n = digitSum(n)
if n == 1:
return True
return False