leetcode-【简单题】Happy Number

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

• 1^2 + 9^2 = 82
• 8^2 + 2^2 = 68
• 6^2 + 8^2 = 100
• 1^2 + 0^2 + 0^2 = 1

链接：

https://leetcode.com/problems/happy-number/

答案：

暴力解决，直接给每个数的每位计算平方和就行，然后把中间的数都记录下来，如果下次出现这个数，就是loop了。

代码：

 #include<vector>

 using std::vector;

 class Solution {
 private:
     vector<int> med;

     bool inMed(int n)
     {
         vector<int>::iterator beg;
         for(beg = med.begin(); beg != med.end(); ++ beg)
         {
             if(*beg == n)
             {
                 return true;
             }
         }

         return false;
     }

     int sum(int n)
     {
         int s = ;
         while(n != )
         {
             int modn = n % ;
             s += modn * modn;
             n = n /;
         }

         return s;
     }

 public:
     bool isHappy(int n)
     {
         if(n ==  || n ==  || n ==  || n == )
         {
             return true;
         }

         med.clear();
         med.push_back(n);

         int result = n;
         bool isLoop = false;
         while( result != )
         {
             result = sum(result);
             if(result !=  && inMed(result))
             {
                 isLoop = true;
                 break;
             }

             med.push_back(result);
         }

         return !isLoop;
     }
 };

代码中的isHappy()方法的最开头我是随便加了几个判断，哈哈，题目中给出的快乐数应该会在后台的测试数据中。