·
📐 Problem
Given a string containing only ()[]{}, determine if it’s well-formed: every opening bracket has a matching closing bracket in the correct order.
Java Solution (Stack + Map)
🧠 Complexity
Time: O(n) — each char is pushed/popped at most once.
Space: O(n) — worst case all openings on the stack.
☝️ Takeaway
This question is a perfect showcase for stack thinking: push on open, pop on close, and match pairs. It’s also great for discussing edge cases (odd length, early closing, leftovers) and why a stack beats a simple counter.
#java #codinginterview #interviewprep #algorithms #datastructures #stack #leetcode #programming #javaprogramming #bigO
Go further with Java certification:
Java👇
Spring👇
SpringBook👇