Topic Connection
https://leetcode.com/problems/happy-number/
Happy numberdescription
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 and replace the number by the Sum of the squares of its digits, and repeat the process until the number equals 1 (where it would stay), or it loops Endl essly in a cycle which does not include 1. Those numbers for which this process ends in 1 is happy numbers.
Example: is a happy number
$1^2 + 9^2 = 82$
$8^2 + 2^2 = 68$
$6^2 + 8^2 = 100$
$1^2 + 0^2 + 0^2 = 1$
Class Solution {Public:bool ishappy (int n) {if (1 = = N) return true;set<int> A;while (true) {int v = 0;do {int i = n % 10;v + = i *;} while (n/=), if (1 = = v) return true;if (A.find (v)! = A.end ()) return false;n = V; A.insert (n);}};
Leetcode Happy Number