Count And Say

The count-and-say sequence is the sequence of integers beginning as follows:

1, 11, 21, 1211, 111221, ...

1 is read off as one 1 or 11.
11 is read off as two 1s or 21.

21 is read off as one 2, then one 1 or 1211.

Given an integer n, generate the nth sequence.

Note: The sequence of integers will be represented as a string.

Example:

if n = 2,
the sequence is 11.

 string appendNext(string str){  
   string out = "";  
   char curr = str[0];  
   int currCount = 1;  
   for(int i = 1; i < str.size(); i++){  
     if (str[i] == curr){  
       currCount++;  
     }  
     else {  
       char chr = currCount + '0';  
       out = out + chr;  
       out = out + curr;  
       curr = str[i];  
       currCount = 1;  
     }  
   }  
   char chr = currCount + '0';  
   out = out + chr;  
   out = out + curr;  
   return out;  
 }  
 string Solution::countAndSay(int n) {  
   if (n == 1) {  
     return "1";  
   }  
   string prev = "1";  
   string result;  
   for (int i = 1; i < n; i++){  
     result = appendNext(prev);  
     prev = result;  
   }  
   return result;  
 }