leetcode.com/problems/happy-number/ Happy Number - LeetCode Level up your coding skills and quickly land a job. This is the best place to expand your knowledge and get prepared for your next interview. leetcode.com 아.. 재귀호출 StackOverflowError 가 났다. class Solution { public boolean isHappy(int n) { if(n == 1){ return true; } if(n == 2 || n == 3){ return false; } int sum = 0; while(n > 0){ sum += M..