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, 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
• 
  

• <pre name="code" class="cpp">bool isHappy(int n) 
  {
      int sum = 0;
      int remain = 0;
      int quotient = 0;
      int i = 0;
      int box[10] = {0};
      
      if(n==1)
          return 1;
      
      while(1)
      {
          remain = n%10;
          sum += remain*remain;
          quotient = n/10;
          
          while(quotient)
          {
              remain = quotient%10;
              sum += remain*remain;
              quotient = quotient/10;
          }
          
          if(sum==1)
              return 1;
          
          if(sum<10)
          {
              if(box[sum] == 1)
                  return 0;
              else
                  box[sum] = 1;
          }
          
          n = sum;
          sum = 0;
      }
  
  }