*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 = 828² + 2² = 686² + 8² = 1001² + 0² + 0² = 1

 

public class Solution { private int getNextHappy(int n) { int sum = 0; while (n != 0) { sum += (n % 10) * (n % 10); n /= 10; } return sum; } public boolean isHappy(int n) { HashSet<Integer> hash = new HashSet<Integer>(); while (n != 1) { if (hash.contains(n)) { return false; } hash.add(n); n = getNextHappy(n); } return true; } }

 

转载于:https://www.cnblogs.com/hygeia/p/4799835.html

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