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.

其實題目很簡單，就是計算個數，並填充到新的陣列中。由於對C++不熟悉，如何給string加上一個字元還不太懂，不過參考了別人的總算寫出來了，但其中機理還是不明白。string型別，除了可以直接加字串或者string變數外，還能加上一個字元！

class Solution {
public:
    string countAndSay(int n) {
        string str;
        str = "1";
        while(--n){
            string temp;
            char pre = str[0];
            int count = 1;
            for(string::size_type i = 1;i < str.size();i++){
                if(str[i] == pre)
                    count++;
                else{
                    char ch = count + '0';
                    temp = temp + ch + pre;
                    pre = str[i];
                    count = 1;
                }
            }
            char ch = count + '0';
            temp = temp + ch + pre;
            str = temp;
        }
        return str;
    }
};