LeetCode 20 – Valid Parentheses | Stack O(n) | Java | Blind 75

LeetCode 20 – Valid Parentheses | Stack Solution in Java | Blind 75 In this video, I explain *LeetCode 20: Valid Parentheses* step by step using the **Stack data structure in Java**. This is an important and frequently discussed coding interview problem that helps you understand **Stack, LIFO, bracket matching, and correct ordering of parentheses**. We are given a string containing: `()` Parentheses `{}` Curly Braces `[]` Square Brackets We need to determine whether the given string is valid. A string is valid when: ✅ Every opening bracket has the correct closing bracket ✅ Brackets close in the correct order ✅ No unmatched opening or closing bracket remains For example: Input: `s = "()[]{}"` Output: `true` Input: `s = "(]"` Output: `false` 🔑 STACK APPROACH Whenever we encounter an opening bracket: `(` `{` `[` we push it into the Stack. When a closing bracket appears, we check the top of the Stack: `)` should match `(` `}` should match `{` `]` should match `[` If the pair matches, we pop the opening bracket from the Stack. If the Stack is empty or the brackets do not match, we return `false`. After processing the complete string, the Stack must be empty for the parentheses to be valid. 📊 COMPLEXITY Time Complexity: *O(n)* Space Complexity: *O(n)* ⏱️ CHAPTERS 00:00 Introduction – LeetCode 20 Valid Parentheses 00:18 Problem Statement & Examples 00:40 Why Stack? 01:50 Stack Approach – Dry Run 04:12 Important Edge Case 05:31 Java Solution in LeetCode Editor 10:16 Time & Space Complexity This problem is useful for understanding: ✅ LeetCode 20 – Valid Parentheses ✅ Stack Data Structure ✅ LIFO Concept ✅ Push & Pop Operations ✅ Bracket Matching ✅ String Problems ✅ Java Solution ✅ Time & Space Complexity ✅ Blind 75 ✅ DSA Interview Preparation ✅ Coding Interview Questions Problem: *LeetCode 20 – Valid Parentheses* Difficulty: *Easy* Topics: *String, Stack* Language: *Java* Series: *Blind 75* 🔗 Problem: https://leetcode.com/problems/valid-p... Try solving the problem yourself before watching the complete solution. The main learning from this problem is how *Stack's Last In First Out (LIFO) property* helps us validate nested brackets in the correct order. If this video helped you, LIKE the video and SUBSCRIBE for more **LeetCode solutions, Blind 75 problems, DSA in Java, Stack problems, algorithms, and coding interview preparation**. 💬 Comment below which LeetCode problem you want me to solve next. Keep Learning, Keep Growing 🚀 #LeetCode20 #ValidParentheses #Stack #Java #Blind75 #DSA #CodingInterview #LeetCodeSolution #StackProblems #InterviewPreparation