leetcode_38

标签：dig   nbsp   class   lis   first   bsp   range   too   wing   

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The count-and-say sequence is the sequence of integers with the first five terms as following:

1.     1
2.     11
3.     21
4.     1211
5.     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 where 1 ≤ n ≤ 30, generate the nth term of the count-and-say sequence.

Note: Each term of the sequence of integers will be represented as a string.

Example 1:

Input: 1
Output: "1"

Example 2:

Input: 4
Output: "1211"

SOLUTION1:
利用itertools中的groupby函数，还原过程：

import itertools


class Solution(object):
    def countAndSay(self, n):
        """
        :type n: int
        :rtype: str
        """
        s = ‘1‘
        for _ in range(n - 1):
            s = ‘‘.join(str(len(list(group))) + digit
                        for digit, group in itertools.groupby(s))
        return s

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leetcode_38

标签：dig   nbsp   class   lis   first   bsp   range   too   wing   

原文地址：https://www.cnblogs.com/francischeng/p/9736302.html