原题地址：https://oj.leetcode.com/problems/count-and-say/
题意：
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.
解题思路：模拟法。
代码：
class Solution: # @return a string def count(self,s): t=‘‘; count=0; curr=‘#‘ for i in s: if i!=curr: if curr!=‘#‘: t+=str(count)+curr curr=i count=1 else: count+=1 t+=str(count)+curr return t def countAndSay(self, n): s=‘1‘ for i in range(2,n+1): s=self.count(s) return s