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38 count and say

admin 11月 14, 2020 0

Description

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.

My Solution

Python

def (self, n):
    """
    :type n: int
    :rtype: str
    """
    def change(num):
        result = ''
        strNum = str(num)
        i = 0
        val = strNum[0]
        appearTime = 0
        while i < len(str(num)):
            if strNum[i] == val:
                appearTime = appearTime + 1
            else:
                result = result+str(appearTime)+val
                val = strNum[i]
                appearTime = 1
            i = i + 1
        return result+str(appearTime)+val
    
    result = 1
    if n == 1:
        return str(result)
    else:
        for i in range(n-1):
            result=change(result)
        return result

想法：遍历