[leetcode]Count and Say @ Python

原題地址：https://oj.leetcode.com/problems/count-and-say/

題意：

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.

解題思路：模擬法。

代碼：

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