Palindrome Partitioning Python Solution

Tested Python solution for LeetCode 131 with 12 pytest cases. Generate a practice environment with lcpy.

LeetCode 131, Medium. Topics: String, Dynamic Programming, Backtracking. View on LeetCode.

Generate this problem as a practice environment: tested reference solution, 12 parametrized pytest cases, and a playground notebook:

lcpy gen -n 131   # by problem number
lcpy gen -s palindrome_partitioning   # by problem name

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Problem

Given a string s, partition s such that every substring of the partition is a palindrome. Return all possible palindrome partitioning of s.

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Examples

Input: s = "aab"
Output: [["a","a","b"],["aa","b"]]

Input: s = "a"
Output: [["a"]]

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Constraints

• 1 <= s.length <= 16
• s contains only lowercase English letters.

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Solution

Reference implementation from solution.py on GitHub, full suite in test_solution.py:

class Solution:
    # Time: O(N * 2^N)
    # Space: O(N)
    def partition(self, s: str) -> list[list[str]]:
        result: list[list[str]] = []
        self._backtrack(s, 0, [], result)
        return result

    def _backtrack(self, s: str, start: int, path: list[str], result: list[list[str]]) -> None:
        if start == len(s):
            result.append(path[:])
            return

        for end in range(start + 1, len(s) + 1):
            substring = s[start:end]
            if self._is_palindrome(substring):
                path.append(substring)
                self._backtrack(s, end, path, result)
                path.pop()

    def _is_palindrome(self, s: str) -> bool:
        return s == s[::-1]

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Complexity

Time	Space
O(N * 2^N)	O(N)

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Tags

NeetCode 150, NeetCode 250, NeetCode All.