LEETCODE 680 C SOLUTION TO VALID PALINDROME 2

Welcome to this in-depth tutorial on LeetCode Problem 680: Valid Palindrome II. In this video, we'll dive deep into understanding the problem, exploring various approaches to solve it, and discussing the optimal solutions. Whether you are a beginner or an experienced programmer, this video aims to provide you with a comprehensive understanding of the problem and enhance your problem-solving skills.
Introduction to the Problem
LeetCode Problem 680, Valid Palindrome II, is a fascinating problem that tests your understanding of string manipulation and algorithms. The problem statement is as follows:
Given a non-empty string s, you may delete at most one character. Judge whether you can make it a palindrome.
A palindrome is a string that reads the same backward as forward. For example, "radar" and "level" are palindromes, while "hello" and "world" are not.
Understanding the Problem
To solve this problem, we need to determine if it's possible to make the given string a palindrome by deleting at most one character. This involves checking the characters from both ends of the string and ensuring they match. If they don't, we need to check if removing one of the mismatched characters results in a palindrome.
Approach 1: Brute Force
The brute force approach involves generating all possible strings by removing one character at a time and checking if any of them is a palindrome. While this approach guarantees a solution, it is not efficient due to its high time complexity, especially for longer strings.
Approach 2: Two-Pointer Technique
A more efficient approach to solving this problem is using the two-pointer technique. This involves using two pointers, one starting from the beginning of the string and the other from the end. We compare the characters at these pointers and move them towards the center of the string. If the characters do not match, we attempt to skip either the left or the right character and check if the remaining substring is a palindrome.
Detailed Steps:
Initialize two pointers, left at the beginning of the string and right at the end.
While left is less than right:
If the characters at left and right match, move both pointers inward.
If the characters do not match, check if skipping the character at left or right results in a palindrome.
If all characters match or one of the substrings formed by skipping a character is a palindrome, return true.
If no valid palindrome is found, return false.
Edge Cases
When solving this problem, it's essential to consider edge cases, such as:
The string is already a palindrome.
The string has only one character.
The string becomes a palindrome by removing the first or the last character.
Time and Space Complexity
The two-pointer approach offers a time complexity of O(n), where n is the length of the string, because each character is checked at most twice. The space complexity is O(1) as no additional space is required beyond the pointers and a few variables.
Conclusion
LeetCode Problem 680, Valid Palindrome II, is a great problem to practice string manipulation and the two-pointer technique. It helps in understanding how to efficiently solve problems involving palindromes and offers a good exercise in optimizing brute force solutions.
In this video, we have explored the problem statement, discussed different approaches, and detailed the optimal solution using the two-pointer technique. We hope this tutorial has provided you with a clear understanding and the confidence to tackle similar problems.
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Additional Tips for Practice
Practice with Variations: Try solving variations of palindrome problems, such as checking for palindromic substrings or counting the number of palindromes in a string. This will help reinforce the concepts learned and improve your problem-solving skills.
Optimize Further: Once you are comfortable with the two-pointer approach, consider exploring further optimizations or alternative methods. Understanding different ways to solve the same problem can provide deeper insights and improve your algorithmic thinking.
Understand the Underlying Concepts: Make sure to grasp the fundamental concepts behind palindromes, string manipulations, and two-pointer techniques. These concepts are widely applicable and can be useful in solving a variety of problems.
Test Thoroughly: Always test your solution with various test cases, including edge cases and large inputs. This helps ensure the robustness and efficiency of your solution.
Summary
Solving LeetCode Problem 680: Valid Palindrome II involves understanding how to manipulate strings and efficiently check for palindromes using the two-pointer technique. By practicing this problem and similar ones, you can enhance your coding skills and prepare for technical interviews.