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g0201_0300.s0202_happy_number.readme.md Maven / Gradle / Ivy

202\. Happy Number

Easy

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