2108. Find First Palindromic String in the Array - Explanation

Problem Link

1. Reverse String

class Solution:
    def firstPalindrome(self, words: List[str]) -> str:
        for w in words:
            if w == w[::-1]:
                return w
        return ""

Time & Space Complexity

• Time complexity: $O(n * m)$
• Space complexity: $O(m)$

Where $n$ is the size of the string array $words$ and $m$ is the average length of a word in the array.

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2. Two Pointers

class Solution:
    def firstPalindrome(self, words: List[str]) -> str:
        for w in words:
            l, r = 0, len(w) - 1
            while w[l] == w[r]:
                if l >= r:
                    return w
                l, r = l + 1, r - 1
        return ""

Time & Space Complexity

• Time complexity: $O(n * m)$
• Space complexity: $O(1)$ extra space.

Where $n$ is the size of the string array $words$ and $m$ is the average length of a word in the array.