38. Count and Say

image.png

注意：int 转 string 要用 to_string
字符串的拼接要用 +=
字符串后接char 要用 push_back

class Solution {
public:
    string countAndSay(int n) {
        string mystring = "1";
        for(int i = 0; i < n-1; i++){
            mystring = say(mystring);
        }
        return mystring;
    }
private:
    string say(string s){
        if(s.size() == 1) return "1" + s; 
        string res = "";
        int cur = 1;
        for(int i = 0; i < s.size();){
            if(s[i] == s[i + 1]){
                cur++;
                i++;
            }
            else{
                res+=(to_string(cur));
                res.push_back(s[i]);
                i++;
                cur = 1;
            }
        }
        return res;
    }
};