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.

第一次出现的是1，第二次出现的是11，第三次出现的是21，第四次出现的是1211，一次类推，求第N次出现的字符串。主要是N次循环，每次循环找到数字出现的字数，然后保存在string中。用到一个数字转化成字符串函数，sprintf(s,”%d”,124354)

class Solution {public:    string countAndSay(int n) {        string result = "1";        string str="";        char strcount[100];        if (n==1)            return result;        for(int i=2; i<=n; i++)        {            str="";            int len = result.length();            int count = 0;            char tmp = result[0];            for(int j=0; j<len; j++)            {                if (tmp == result[j])                {                    count++;                }                else                {                    sprintf(strcount,"%d",count);                    str = str + strcount + tmp;                    count = 0;                    tmp = result[j];                    j--;                }            }            sprintf(strcount,"%d",count);            str = str + strcount + tmp;            result = str;        }        return str;    }};