202. Happy Numberleetcodejava，hashSet,算法 _leetcode

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202. Happy Number

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

【202. Happy Numberleetcodejava，hashSet,算法】题意：
写一个算法来判断一个数字是否“快乐”。
一个愉快的数字是由下面的过程定义的一个数字：从任何正整数开始，用它的数字的平方代替数字，重复这个过程直到数字等于1（它将停留在哪里），或者在一个不包括1的循环中循环。这个过程以1结尾的数字是快乐数字。
例子：19是一个快乐的数字。

1 public class Solution { 2private int getHappyNumber(int n){ 3int sum=0; 4while(n!=0){ 5sum+=(n%10)*(n%10); 6n=n/10; 7} 8return sum; 9} 10public boolean isHappy(int n) { 11HashSet< Integer> hash=new HashSet< Integer> (); 12while(n!=1){ 13if(hash.contains(n)) 14return false; 15else{ 16hash.add(n); 17n=getHappyNumber(n); 18} 19} 20return true; 21} 22 }