Stack / Queue

Stacks (last-in-first-out) and queues (first-in-first-out) control the order in which work is processed. Use a stack for nesting, matching, and undo-style backtracking; use a queue for level-by-level or first-come-first-served processing.

12 LeetCode problems solved with the Stack / Queue pattern. Practice them with spaced repetition so the pattern sticks.

• Asteroid CollisionMEDIUM · O(n)
• Baseball GameEASY · O(n)
• Basic CalculatorHARD · O(n)
• Decode StringMEDIUM · O(n)
• Evaluate Reverse Polish NotationMEDIUM · O(n)
• Longest Valid ParenthesesHARD · O(n)
• Min StackMEDIUM · O(1)
• Number of Recent CallsEASY · O(1)
• Remove All Adjacent Duplicates In StringEASY · O(n)
• Removing Stars From a StringMEDIUM · O(n)
• Simplify PathMEDIUM · O(n)
• Valid ParenthesesEASY · O(n)