leetcode

Count and Say

Count and Say

groupby Version - 40ms

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

Prev Version - 52ms

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class Solution:
    def countAndSay(self, n):
        """
        :type n: int
        :rtype: str
        """
        ret = '1'
        for _ in range(n - 1):
            prev = ret
            ret = ''
            j = 0
            while j < len(prev):
                cur = prev[j]
                cnt = 1
                j += 1
                while j < len(prev) and prev[j] == cur:
                    cnt += 1
                    j += 1
                ret += str(cnt) + str(cur)
        return ret

test code

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In [472]: s = Solution(); t = s.countAndSay(8); print(t)
1113213211

leet code