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Leetcode202-happyNumber

Posted on Edited on In Views: Valine:
Solution Report of LeetCode Acceptted

Description

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

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Input: 19
Output: true
Explanation: 
12 + 92 = 82
82 + 22 = 68
62 + 82 = 100
12 + 02 + 02 = 1

Solution

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class Solution {
    public boolean isHappy(int n) {
        if (n == 0) return false;
        if (n == 1) return true;
        HashSet<Integer> set = new HashSet<>();
        set.add(n);
        while(n != 1){
            int sum = 0;
            while(n != 0){
                sum += Math.pow((n % 10), 2);
                n /= 10;
            }
            if (set.contains(sum)) return false;
            set.add(sum);
            n = sum;
        }
        return true;
    }
}