1. 题目
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
2.解题方案class Solution {public:bool isHappy(int n) {if(n < 1){return false;}if(n == 1){return true;}unordered_set<int> showNums;showNums.insert(n);while(true){int sum = 0;while(n != 0){int oneDigital = n % 10;n = n / 10;sum = sum + oneDigital * oneDigital;}if(sum == 1){return true;}else{if(showNums.find(sum) == showNums.end()){showNums.insert(sum);}else{return false;}}n = sum;}}};思路：用求余和除以10得到每一位数，相加进行判断。这里还用了一个set来存储已经出现的数字，如果重复了，说明就不是一个happy number。
，而现在我喜欢深邃的夜空，包容一切的黑暗和隐忍，留下眼泪也没人看见。
