File: find-first-palindromic-string-in-the-array/solution.py

Date: 2026-06-06

Time: 16:37

find-first-palindromic-string-in-the-array/solution.py

Purpose

This file implements the solution to LeetCode 2108: Find First Palindromic String in the Array. It owns the single responsibility of scanning a list of strings and returning the first one that reads the same forwards and backwards, or "" if none qualifies.

Key Components

Solution.firstPalindrome(self, words: List[str]) -> str — The core algorithm. Iterates through words in order, checking each against its reverse via Python's slice [::-1]. Returns immediately on the first match (short-circuit), or "" after exhausting the list.

minimizeTheDifference(words: List[str]) -> str — A module-level wrapper that delegates to Solution().firstPalindrome. The name is a misnomer — it doesn't minimize any difference. This is likely a copy-paste artifact from the project's code generation pipeline, where a wrapper function is required by the test harness under a standardized (but incorrectly named) entry point.

Patterns

• LeetCode class convention: The Solution class with a single method matches LeetCode's expected submission format.
• Wrapper delegation: The module-level function instantiates Solution and forwards the call, decoupling the test harness from the class interface.
• Early return on match: The for/if/return pattern avoids scanning the entire list when a palindrome is found early.

Dependencies

Imports: typing.List — used only for type annotations. No runtime dependencies beyond the standard library.

Imported by: The "Imported By" list in the prompt is misleading — it shows ~400+ test files from unrelated problems. This is likely an artifact of how the dependency graph was extracted (perhaps matching on the Solution class name or the import path pattern). The actual consumer is find-first-palindromic-string-in-the-array/test_solution.py.

Flow

1. Caller invokes minimizeTheDifference(words) (or Solution().firstPalindrome(words) directly)

2. Linear scan over words: for each word, compare word == word[::-1]

3. First palindrome found → return it immediately

4. No palindrome in entire list → return ""

Complexity: O(n * m) where n = number of words and m = average word length. The [::-1] comparison is O(m) per word. Space is O(m) for the reversed copy.

Invariants

• The return value is always a member of words or "" — never None, never a modified string.
• Ordering is preserved: if multiple palindromes exist, the one with the lowest index wins.
• The input list is never mutated.

Error Handling

None. The function assumes valid input per the LeetCode contract (non-empty list of non-empty lowercase strings). An empty words list would correctly return "" since the loop body never executes.