LeetCode 20: Valid Parentheses | Stack Solution in Java | Easy DSA

In this video, I’m solving *LeetCode 20 – Valid Parentheses* using Java and a Stack. The problem is to check whether the given string of parentheses is valid. The brackets must be closed with the correct type and in the correct order. For this problem, I used a **Stack**. Whenever I find an opening bracket like `(`, `{`, or `[`, I push it into the stack. When I find a closing bracket, I check whether it matches the opening bracket at the top of the stack. If it doesn't match, the string is not valid. At the end, the stack should be empty for the parentheses to be valid. Examples `()` → `true` `()[]{}` → `true` `(]` → `false` `([])` → `true` `([)]` → `false` Complexity *Time Complexity: O(n)* We traverse the string once, and each bracket is processed at most once. *Space Complexity: O(n)* In the worst case, all characters can be opening brackets, so the stack can contain up to `n` characters. *Problem:* LeetCode 20 – Valid Parentheses *Language:* Java *Data Structure:* Stack *Difficulty:* Easy If you're preparing for **DSA, coding interviews, or placements**, this is an important problem to understand because it teaches how to use a Stack to handle brackets and maintain their correct order. #LeetCode #LeetCode20 #ValidParentheses #Java #DSA #Stack #CodingInterview #PlacementPreparation #JavaProgramming