Solution Explanation: Find First Palindromic String in the Array

The problem asks to find the first palindromic string within a given array of strings. A palindromic string reads the same forwards and backward. The solution involves iterating through the array and checking each string for palindrome properties.

Approach:

The most efficient approach is to iterate through the array of strings and check each string for the palindrome property. For each string, we can use a two-pointer technique to compare characters from the beginning and end, moving towards the middle. If all corresponding characters match, the string is a palindrome, and we return it. If no palindrome is found after iterating through all strings, we return an empty string.

Time Complexity Analysis:

• Outer Loop: The outer loop iterates through the array of strings, which has a length of n. This contributes O(n) to the time complexity.
• Inner Loop (Palindrome Check): The inner loop (for palindrome checking) iterates at most m/2 times, where m is the length of the current string. In the worst case, we might need to check all strings, so we consider the average length of strings to be m. Therefore, the palindrome check contributes O(m) time complexity.
• Overall: Combining the outer and inner loops, the overall time complexity becomes O(n * m), where n is the number of strings and m is the average length of a string. In the best-case scenario (the first string is a palindrome), the complexity is O(m).

Space Complexity Analysis:

The algorithm uses a constant amount of extra space regardless of the input size. We use a couple of pointers for the palindrome check and some temporary variables. Therefore, the space complexity is O(1), constant space.

Code Implementation (Python):

def firstPalindrome(words: list[str]) -> str:
    """
    Finds the first palindromic string in an array of strings.
 
    Args:
        words: A list of strings.
 
    Returns:
        The first palindromic string in the array, or an empty string if none exists.
    """
    for word in words:
        if word == word[::-1]:  # Efficient palindrome check using slicing
            return word
    return ""
 

Code Implementation (Other Languages):

The implementations in other languages follow a similar structure. They iterate through the array and use a two-pointer approach or string reversal to identify palindromes. The core logic remains consistent across different programming languages. The code examples provided in the original response show implementations in Java, C++, Go, TypeScript, Rust, and C. These examples also demonstrate similar time and space complexities.

Example Usage:

words1 = ["abc", "car", "ada", "racecar", "cool"]
print(firstPalindrome(words1))  # Output: ada
 
words2 = ["notapalindrome", "racecar"]
print(firstPalindrome(words2))  # Output: racecar
 
words3 = ["def", "ghi"]
print(firstPalindrome(words3))  # Output: 

This demonstrates how the function correctly identifies the first palindromic string or returns an empty string when no palindrome exists.