38. Count and Say

原创于 2016-07-26 19:38:23 发布 · 306 阅读

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本文介绍了一种生成计数并说序列的方法，通过Python实现，解析了LeetCode上第38题的具体解决方案。该算法接受一个整数n作为输入，并生成对应的计数并说序列。

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38. Count and Say

Leetcode link for this question

Discription:

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.

Analyze:

Code 1:

class Solution(object):
    def countAndSay(self, n):
        """
        :type n: int
        :rtype: str
        """
        def fun(s):
            p1,p2=0,0
            re=''
            for i,v in enumerate(s):
                p2=i
                if s[p1]==s[p2]:
                    continue
                else:
                    re=re+str(p2-p1)+s[p1]
                    p1=p2
            re=re+str(p2-p1+1)+s[p1]
            return re

        s=str(1)
        for i in range(n-1):
            s=fun(s)
        return s