palindrome-permutation-ii

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267. Palindrome Permutation II (Medium)

Given a string s, return all the palindromic permutations (without duplicates) of it. Return an empty list if no palindromic permutation could be form.

Example 1:

Input: "aabb"
Output: ["abba", "baab"]

Example 2:

Input: "abc"
Output: []

Related Topics

[Hash Table] [String] [Backtracking]

Similar Questions

1. Next Permutation (Medium)
2. Permutations II (Medium)
3. Palindrome Permutation (Easy)

Hints

Hint 1

If a palindromic permutation exists, we just need to generate the first half of the string.

Hint 2

To generate all distinct permutations of a (half of) string, use a similar approach from: Permutations II or Next Permutation.