937. Reorder Data in Log Files

You are given an array of logs. Each log is a space-delimited string of words, where the first word is the identifier.

There are two types of logs:

  • Letter-logs: All words (except the identifier) consist of lowercase English letters.
  • Digit-logs: All words (except the identifier) consist of digits.

Reorder these logs so that:

  1. The letter-logs come before all digit-logs.
  2. The letter-logs are sorted lexicographically by their contents. If their contents are the same, then sort them lexicographically by their identifiers.
  3. The digit-logs maintain their relative ordering.

Return the final order of the logs.

Example 1:

Input: logs = ["dig1 8 1 5 1","let1 art can","dig2 3 6","let2 own kit dig","let3 art zero"]
Output: ["let1 art can","let3 art zero","let2 own kit dig","dig1 8 1 5 1","dig2 3 6"]
The letter-log contents are all different, so their ordering is "art can", "art zero", "own kit dig".
The digit-logs have a relative order of "dig1 8 1 5 1", "dig2 3 6".

Example 2:

Input: logs = ["a1 9 2 3 1","g1 act car","zo4 4 7","ab1 off key dog","a8 act zoo"]
Output: ["g1 act car","a8 act zoo","ab1 off key dog","a1 9 2 3 1","zo4 4 7"]


  • 1 <= logs.length <= 100
  • 3 <= logs[i].length <= 100
  • All the tokens of logs[i] are separated by a single space.
  • logs[i] is guaranteed to have an identifier and at least one word after the identifier.

Wrong Solution

class Solution:
    def reorderLogFiles(self, logs):
        return sorted(logs, key = lambda l: '0'+" ".join(l.split()[1:])+l.split()[0] if l.split()[1].isalpha() else '1')

Probably not the most efficient because we split the same line multiple times, but it looks like Python does it pretty efficiently …

Using the standard approach, with a lambda function:

check the l[1] element, if it’s numeric, return '0' + l[1:] + l[0], otherwise returns '1'.

That way the text entries will be shown first sorted based on l[1:] + l[0] and the other entries (presumably numeric) will follow in the original order.


class Solution:
    def reorderLogFiles(self, logs):
        l = filter(lambda l: l[l.find(" ") + 1].isalpha(), logs)
        d = filter(lambda l: l[l.find(" ") + 1].isdigit(), logs)
        return sorted(l, key = lambda x: (x[x.find(" "):], x[:x.find(" ")])) + list(d)

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