- Write an algorithm to determine if a number
- 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.
nis a happy number, and
- This challenge corresponds to LeetCode #202.
1 <= n <= 231 - 1
Input: n = 19 Output: true Explanation: 12 + 92 = 82 82 + 22 = 68 62 + 82 = 100 12 + 02 + 02 = 1
Input: n = 2 Output: false
Below is my solution and some test cases. This solution has a logarithmic time complexity O(log n) and a constant space complexity O(1), where n is the length of the input list.