Count and Say 【leetcode】

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 n^th sequence.

Note: The sequence of integers will be represented as a string.

两个变量去扫描字符串，temp表示当前的值，n表示当前的值的个数。

class Solution {public:    string countAndSay(int n) {        string a,b;        a="1";        for(int i=2;i<=n;++i)        {            b="";            int len=a.size(),n=1;            char temp=a[0];            for(int j=1;j<len;++j)            {                if(a[j]!=temp)                {                    b+='0'+n;                    b+=temp;                    temp=a[j];                    n=1;                }                else                    n++;                            }            b+='0'+n;            b+=temp;            swap(a,b);        }        return a;    }};