Leetcode 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.

递推即可，

每count and say一次，统计字符串中连续字符出现的次数，然后将其转化成字符串即可

class Solution {
public:
    string countAndSay(int n) {
        string init = "1";
        for(int i = 1 ; i < n ; ++ i){
            int cnt =1;
            char pre = init[0];
            string str = "";
            for(int j = 1 ; j <  init.length(); ++ j){
                if(init[j]!=pre){
                    str+=to_string(cnt)+pre;
                    cnt = 1;
                    pre = init[j];
                }else{
                    cnt++;
                }
            }
            str+=to_string(cnt)+pre;
            init = str;
        }
        return init;
    }
};