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Palindrome Partitioning

Given a string, partition it into a collection of substrings such that every substring in the collection is a palindrome. The goal is to find all possible ways to partition the string. This problem is a classic example of exploring combinatorial possibilities and often involves recursive or dynamic programming approaches.

Problem Description

You are tasked with writing a function that takes a string as input and returns a list of all possible palindrome partitions. A palindrome is a word, phrase, number, or other sequence of characters that reads the same backward as forward (e.g., "madam", "racecar").

Requirements:

  1. The function should accept a single string s as input.
  2. The function should return a list of lists, where each inner list represents a valid palindrome partition of the input string.
  3. Each element within an inner list must be a substring of s.
  4. Every substring in a partition must be a palindrome.
  5. The concatenation of the substrings in any given partition must reconstruct the original string s.

Edge Cases to Consider:

  • An empty input string.
  • A string consisting of a single character.
  • A string that is itself a palindrome.
  • A string where no palindromic partitions are possible (except for individual characters).

Examples

Example 1:

Input: "aab"
Output: [["a","a","b"],["aa","b"]]
Explanation:
- ["a","a","b"]: "a", "a", and "b" are all palindromes. Concatenating them gives "aab".
- ["aa","b"]: "aa" and "b" are palindromes. Concatenating them gives "aab".

Example 2:

Input: "a"
Output: [["a"]]
Explanation: A single character string is always a palindrome.

Example 3:

Input: ""
Output: [[]]
Explanation: An empty string has one partition, which is an empty list of substrings.

Example 4:

Input: "aba"
Output: [["a","b","a"],["aba"]]
Explanation:
- ["a","b","a"]: "a", "b", and "a" are palindromes. Concatenating them gives "aba".
- ["aba"]: "aba" is a palindrome. Concatenating it gives "aba".

Constraints

  • 1 <= s.length <= 16 (The length of the input string will be between 1 and 16, inclusive.)
  • s consists only of lowercase English letters.
  • The algorithm should be reasonably efficient for the given constraints.

Notes

  • You will likely need a helper function to efficiently check if a given substring is a palindrome.
  • Consider how to systematically explore all possible partitions. Backtracking or a similar recursive approach is often well-suited for this type of problem.
  • The order of partitions in the output list does not matter. The order of substrings within each partition does matter, as it must reconstruct the original string.
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