Happy Number

Happy Number

 Total Accepted: 24694 Total Submissions: 77594My Submissions

Question Solution 

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

• 12 + 92 = 82
• 82 + 22 = 68
• 62 + 82 = 100
• 12 + 02 + 02 = 1

题目大意：判断一个数是否是快乐数

  bool isHappy(int n) {    int digital;    int iterat = 0;    if(n == 1)        return true;    if(n == 42)        return false;    while(n)    {        digital = n%10;        iterat += digital*digital;        n = n/10;    }        isHappy(iterat);}

运行时间：0ms

题目中的42的来由，测试时打印发现，不是快乐数的数会出现一个循环，其中就有42，算是运气把。