leetcode_38. Count and Say

題目：

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 n^th sequence.

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

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浪費了點時間，count搞錯了。要注意使用的時候是使用變化之前的還是變化之後的。

貼代碼

class Solution {
public:
    string countAndSay(int n) {
        string outstring = "1";
        for(int i = 0; i < n-1; ++ i){
            outstring = Sayout(outstring);
        }
        return outstring;
    }
    string Sayout(string s){
        string sout;
        char nowchar, prechar;
        prechar = '*';
        int count = 0;
        if(s.size() == 1){
            return "11";
        }
        
        for(int i = 0; i < s.size(); ++i){
            nowchar = s[i];
            if(nowchar != prechar){
                
                if(prechar != '*'){
                    sout += (to_string(count)+prechar);
                }
                count = 1;
                prechar = nowchar;
            }else{
                count++;
            }
        }
        sout += (to_string(count)+s[s.size()-1]);
        return sout;
    }

};