Stack vs Queue Comparison
See how the same operations produce different results
Perform the same operations on both Stack and Queue to see how they behave differently.
Remove returns: most recently added
Remove returns: first added (oldest)
After adding elements 1, 2, 3 in order:
- • Stack removes in order: 3, 2, 1 (reverse order - LIFO)
- • Queue removes in order: 1, 2, 3 (same order - FIFO)
Click "Demo: Add 1,2,3 then Remove All" to see this in action!
| Feature | Stack | Queue |
|---|---|---|
| Principle | LIFO (Last-In, First-Out) | FIFO (First-In, First-Out) |
| Insert Operation | push() - adds to top | enqueue() - adds to rear |
| Remove Operation | pop() - removes from top | dequeue() - removes from front |
| View Operation | peek() - views top | peek() - views front |
| Time Complexity | O(1) for all ops | O(1) for all ops |
| Java Interface | Deque<E> (preferred) | Queue<E> |
| Java Implementation | ArrayDeque, LinkedList | LinkedList, ArrayDeque |
| Analogy | Stack of plates | Line at a store |
| Best For | Undo, backtracking, recursion | Scheduling, BFS, buffers |
- ✓You need to reverse order
- ✓Most recent item matters most
- ✓Implementing undo/redo
- ✓Parsing expressions/brackets
- ✓Implementing DFS traversal
- ✓Converting recursion to iteration
- ✓First-come, first-served matters
- ✓Processing in arrival order
- ✓Implementing task scheduling
- ✓Buffering data streams
- ✓Implementing BFS traversal
- ✓Level-order processing
- ✓Elements have different priorities/importance
- ✓Need to always process the "most important" item next
- ✓Implementing Dijkstra's or A* algorithms
- ✓Event-driven simulation (process earliest event first)
Stack Examples
Pages visited are pushed. Back button pops to show previous page.
Actions pushed to undo stack. Undo pops most recent action.
Each function call pushes a frame. Return pops it.
Queue Examples
Documents printed in order they were sent.
Customers served in order they arrived.
CPU processes tasks in submission order (basic scheduling).
1.Stack = LIFO (think of a stack of plates)
2.Queue = FIFO (think of a waiting line)
3.Both have O(1) time for all basic operations
4.Use Stack for undo, backtracking, DFS
5.Use Queue for scheduling, buffering, BFS
6.Use PriorityQueue when order depends on priority