1 题目描述

The count-and-say sequence is the sequence of integers with the first five terms as following:

1.     1
2.     11
3.     21
4.     1211
5.     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 term of the count-and-say sequence.

Note: Each term of the sequence of integers will be represented as a string.

难度：Easy

2 题目样例

Example 1:

Input: 1
Output: "1"

Example 2:

Input: 4
Output: "1211"

3 题意分析

将数字从1开始，将当前数字转化为口语对应的数字。比如1口语是1个1，记作11；11读作2个1，记作21；21读作1个2，1个1，记作1211……

4 思路分析

一个一个数过去即可。

代码实现如下

class Solution 

{
    
public:
    
        string countAndSay(int n) 

    {

        if (n == 0) return "";

        string res = "1";

        while (--n) 

        {
            string cur = "";

            for (int i = 0; i < res.size(); i++) 

            {
                int count = 1;

                 while ((i + 1 < res.size()) && (res[i] == res[i + 1]))

                 {
                    count++;    

                    i++;
                }

                cur += to_string(count) + res[i];

            }

            res = cur;

        }

        return res;
    }
};

5 后记

这个题目我不是很喜欢…因为没什么技术含量。