leetcode 202. Happy Number

Seawolf

1. Write an algorithm to determine if a number is "happy".
   
2. 
   
3. 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.
   
4. 
   
5. Example:
   
6. 
   
7. Input: 19
   
8. Output: true
   
9. Explanation:
   
10. 12 + 92 = 82
    
11. 82 + 22 = 68
    
12. 62 + 82 = 100
    
13. 12 + 02 + 02 = 1

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1. class Solution {
   
2. 
   
3.     public boolean isHappy(int n) {
   
4.         
   
5.         int sum =0;
   
6.         
   
7.         if(n == 1 || n == 7){
   
8.             
   
9.             return true;
   
10.         }
    
11.         
    
12.         else if ( n < 10){
    
13.             
    
14.             return false;
    
15.         }
    
16.         
    
17.         else{
    
18.         
    
19.         while(n > 0){
    
20.             
    
21.             sum += (n % 10) * (n % 10);
    
22.             n = n /10;
    
23. 
    
24.         }
    
25.         }
    
26.         return isHappy(sum);
    
27.     }
    
28.    
    
29. }

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