[leetcode] 893. Groups of Special-Equivalent Strings

[leetcode] 893. Groups of Special-Equivalent Strings

Description

You are given an array A of strings.

A move onto S consists of swapping any two even indexed characters of S, or any two odd indexed characters of S.

Two strings S and T are special-equivalent if after any number of moves onto S, S == T.

For example, S = “zzxy” and T = “xyzz” are special-equivalent because we may make the moves “zzxy” -> “xzzy” -> “xyzz” that swap S[0] and S[2], then S[1] and S[3].

Now, a group of special-equivalent strings from A is a non-empty subset of A such that:

Every pair of strings in the group are special equivalent, and;The group is the largest size possible (ie., there isn’t a string S not in the group such that S is special equivalent to every string in the group)Return the number of groups of special-equivalent strings from A.

Example 1:

Input: ["abcd","cdab","cbad","xyzz","zzxy","zzyx"]Output: 3Explanation: One group is ["abcd", "cdab", "cbad"], since they are all pairwise special equivalent, and none of the other strings are all pairwise special equivalent to these.The other two groups are ["xyzz", "zzxy"] and ["zzyx"]. Note that in particular, "zzxy" is not special equivalent to "zzyx".

Example 2:

Input: ["abc","acb","bac","bca","cab","cba"]Output: 3

Note:

1 <= A.length <= 10001 <= A[i].length <= 20All A[i] have the same length.All A[i] consist of only lowercase letters.

分析

题目的意思是：分类特别相等的字符串，这道题我看了好多遍没看明白，后面发现是奇数位置和偶数位置排序后构成的数相等才算相等，所以这里用一个set集合来统计一下个数就行了。如果看懂题目才好做，否则估计跟我一样郁闷了，哈哈哈。

代码

class Solution: def numSpecialEquivGroups(self, A: List[str]) -> int: signature = set() for s in A: signature.add(''.join(sorted(s[::2]))+''.join(sorted(s[1::2]))) return len(signature)

参考文献

​​[LeetCode] Python O(n * k lg k) sol. by signature. 90%+ [w/ Hint]​​

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