[leetcode] 【字符串】 38. 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.

题意

按照计数方式来生成下一个数值，比如1的下一个数值就是1个1  表示为11

11的下一个数是2个1  表示为21

21的下一个数为1个2      1个1     表示为1211

以此类推，n表示第n个数。

题解

一个个迭代计算，迭代n次

class Solution {public:    string tran(string cur)    {        string res;        char key=cur[0];        int times=1;        for(int i=1;i!=cur.size();i++)        {            if(cur[i]==key)                times++;            else            {                char stimes=times+'0';                res=res+stimes+key;                key=cur[i];                times=1;            }        }        char stimes=times+'0';        res=res+stimes+key;        return res;    }    string countAndSay(int n) {        string cur="1";        while(--n)            cur=tran(cur);        return cur;    }};