Stacks & Queues
Master stack and queue data structures with implementation and problem-solving techniques.
Showing 20 of 20 questions
Easy: 5 Medium: 11 Hard: 4
| Question | Difficulty |
|---|---|
Implement Queue using Stacks Implement a queue using two stacks with O(1) amortized time complexity for all operations. | Easy |
Implement Queue Implement a queue using arrays or linked lists with O(1) time complexity for all operations. | Easy |
Implement Stack using Queues Implement a stack using two queues with O(1) amortized time complexity for all operations. | Easy |
Implement Stack Design and implement a stack data structure with push, pop, top, and empty operations | Easy |
Valid Parentheses Determine if the input string has valid brackets that are properly opened and closed | Easy |
Celebrity Problem Find the celebrity in a party of n people using the minimum number of questions. | Medium |
Daily Temperatures Find the number of days until a warmer temperature for each day. | Medium |
Decode String Decode a string encoded with the format k[encoded_string]. | Medium |
Design Circular Queue Design a circular queue with fixed size that supports enqueue, dequeue, front, rear, isEmpty, and isFull operations. | Medium |
Evaluate Reverse Polish Notation Evaluate the value of an arithmetic expression in Reverse Polish Notation. | Medium |
Min Stack Design a stack that supports push, pop, top, and retrieving the minimum element in constant time | Medium |
Minimum Insertions to Balance Parentheses Find minimum insertions needed to balance parentheses string | Medium |
Next Greater Element Find the next greater element for each element in an array. | Medium |
Remove K Digits Remove k digits from a number to make it as small as possible | Medium |
Rotten Oranges Problem Find the minimum time for all oranges to rot using BFS | Medium |
Stock Span Problem Calculate the span of stock prices for each day | Medium |
Expression Evaluation Evaluate mathematical expressions with proper operator precedence and parentheses. | Hard |
Largest Rectangle in Histogram Find the largest rectangle that can be formed in a histogram | Hard |
Max Stack Design a stack that supports push, pop, top, peekMax, and popMax operations | Hard |
Sliding Window Maximum Find the maximum element in each sliding window of size k. | Hard |