Leetcode[202]-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 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:19 is a happy number

1 2 + 9 2 = the
8 2 + 2 2 = the
6 2 + 8 2 = -
1 2 + 0 2 + 0 2 =1

Credits:
Special thanks to @mithmatt and @ts for adding the problem and creating all test cases.

Analysis : The topic is about any positive integer, the sum of the squares of the number on each digit, if the final convergence is 1, then the number is happy numbers, or the program may start from a number of cycles into the loop.

Here we use a hash table to store the numbers that have already occurred, and return False if they occur the next time.

classSolution { Public:BOOLIshappy (intN) {if(n==1)return true; map<int,int>Nums while(n>0){intNumber =0; while(n) {Number + = (n%Ten) * (n%Ten); N/=Ten; }if(Number = =1)return true;Else if(Nums.find (number)!=nums.end ())return false;            n = number; Nums[n] =1; }    }};

In addition, there is a simple algorithm:

class Solution {public:    bool isHappy(int n) {        while(n>6){              intnext0;              while(n){                next+=(n%10)*(n%10);                 n/=10;            }              next;          }          return n==1;      }};

Leetcode[202]-happy number