38.Count and Say

2019-04-16

38.Count and Say

  1. Count and SayEasy7085419FavoriteShare

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

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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:

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Input: 1
Output: "1"

Example 2:

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Input: 4
Output: "1211"

Code:

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class Solution(object):
    def countAndSay(self, n):
        """
        :type n: int
        :rtype: str
        """
        s = '1'
        for _ in range(n-1):
            let, temp, count = s[0], '', 0
            for l in s:
                if let == l:
                    count += 1
                else:
                    temp += str(count)+let
                    let = l
                    count = 1
            temp += str(count)+let
            s = temp
        return s

# count计数
# 遇到新数，将之前合起来，直接计数count=1
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