LeetCode 249. Group Shifted Strings-优快云博客

本文链接：https://blog.youkuaiyun.com/taoqick/article/details/106491971

本文探讨了一种基于字符串移位的算法，该算法能够将属于同一移位序列的字符串进行分组。通过实例演示了如何使用Python实现这一算法，包括详细的操作流程和代码示例。文章展示了如何通过计算每个字符串的移位键来识别其所属的移位序列，并最终按序列分组。

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Given a string, we can "shift" each of its letter to its successive letter, for example: "abc" -> "bcd". We can keep "shifting" which forms the sequence:

"abc" -> "bcd" -> ... -> "xyz"

Given a list of strings which contains only lowercase alphabets, group all strings that belong to the same shifting sequence.

Example:

Input: ["abc", "bcd", "acef", "xyz", "az", "ba", "a", "z"],
Output: 
[
  ["abc","bcd","xyz"],
  ["az","ba"],
  ["acef"],
  ["a","z"]
]

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虽然过了，操作有点长：

from collections import defaultdict
class Solution:
    def groupStrings(self, strings: List[str]) -> List[List[str]]:
        def get_key(s):
            res = ''
            delta = ord(s[0])-ord('a')
            for ch in s:
                if (ord(ch)-delta >= ord('a')):
                    res += chr(ord(ch)-delta)
                else:
                    res += chr(ord(ch)-delta+26)
            return res
        
        res = []
        dic = defaultdict(list)
        for s in strings:
            key = get_key(s)
            dic[key].append(s)
        for k,v in dic.items():
            res.append(sorted(v))
        return res

从Discussion学的精简codes：

from collections import defaultdict
class Solution:
    def groupStrings(self, strings):
        groups = collections.defaultdict(list)
        for s in strings:
            groups[tuple((ord(c) - ord(s[0])) % 26 for c in s)] += s,
        return groups.values()