44-Count and Say

1. Count and Say My Submissions QuestionEditorial Solution
   
   Total Accepted: 79863 Total Submissions: 275285 Difficulty: Easy
   
   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.

Submission Details

18 / 18 test cases passed.

Status: Accepted

Runtime: 0 ms

beats:69.03%

思路：看懂题目即可，后一个数由前一个数根据规则生成

class Solution {
public:
    string countAndSay(int n) {
        vector<char> vec;
        int i=2;
        string pres("1");
        if(n<=1)return pres;
        pres="11";
        while(i++<n){
            int count=1;
            string s;
            for(int j=0;j<pres.size();++j)
                if(pres[j]==pres[j+1]&&count<9)count++;//<9不知会不会出现大于9个一样数的情况
                else{
                    s.push_back(count+'0');
                    s.push_back(pres[j]);
                    count=1;
                }
            pres = s;
        }
        return pres;
    }
};