题目：

题解：

class Solution {private static Set<Integer> cycleMembers =new HashSet<>(Arrays.asList(4, 16, 37, 58, 89, 145, 42, 20));public int getNext(int n) {int totalSum = 0;while (n > 0) {int d = n % 10;n = n / 10;totalSum += d * d;}return totalSum;}public boolean isHappy(int n) {while (n != 1 && !cycleMembers.contains(n)) {n = getNext(n);}return n == 1;}
}