[LeetCode] 202. Happy Number

轉自LeetCode

Write an algorithm to determine if a number 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, and 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 numbers.

Example: 19 is a happy number

• 12 + 92 = 82
• 82 + 22 = 68
• 62 + 82 = 100
• 12 + 02 + 02 = 1

<Solution>
這題的想法如下

• 按著題目的要求去計算，如果 n = 1 了，就結束迴圈，回傳答案

• 用一個 set 來記錄出現過的數字，如果又出現一樣的數字，代表無法結束，跳出迴圈

code 如下(參考資料)
c++

kotlin