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Data Structures & Algorithms · Module 5 of 10

Stacks and queues

LIFO and FIFO structures.

📖 Key ideas

  1. Stack: last in, first out (push, pop, top).
  2. Queue: first in, first out (enqueue, dequeue).
  3. Deque allows both ends.
  4. Stacks: undo, bracket matching, function calls.
  5. Queues: scheduling, BFS, buffering.
💡 Real-life example: A stack is a pile of plates; a queue is a line at a ticket counter.
StackLIFO structure
QueueFIFO structure
DequeDouble-ended queue
Monotonic stackStack kept in sorted order