Happy Number

A "Happy Number" is defined as a number that after finite number of "steps" - where we sum the square of each digit each time - the result is a 1. Given a number n, determine whether it is a happy number.

As a challenge, complete this question under constant space.

Parameters

• n: The number to check.

Result

• true or false, depending on whether this number is a happy number.

Examples

Example 1

Input: n = 19

Output: true

Explanation:

1^2 + 9^2 = 82
8^2 + 2^2 = 68
6^2 + 8^2 = 100
1^2 + 0^2 + 0^2 = 1

Example 2

Input: n = 2

Output: false

Explanation:

2^2 = 4
4^2 = 16
1^2 + 6^2 = 37
3^2 + 7^2 = 58
5^2 + 8^2 = 89
8^2 + 9^2 = 145
1^2 + 4^2 + 5^2 = 42
4^2 + 2^2 = 18
1^2 + 8^2 = 65
6^2 + 5^2 = 61
6^2 + 1^2 = 37
...

Constraints

• 1 <= n < 2^31

Try it yourself

Solution