Stacks & Monotonic Stacks
Last in, first out: the right tool whenever the most recent thing matters most.
5 lessons · ~48 min · free
By the end you can
- Know when last-in-first-out is the natural shape of a problem
- Match and validate nested brackets in one pass
- Simulate nested structures without recursion
- Solve next-greater and daily-temperatures problems with a monotonic stack
- Choose between increasing and decreasing stacks on sight
Lessons
- 1Last in, first out8 minPush, pop, and why undo buttons, call stacks, and matching problems all share one shape.
- 2Matching and nesting10 minValid parentheses done right: the most recent open bracket is the only one that can close.
- 3Monotonic stacks12 minNext greater element and daily temperatures: a stack of values still waiting for their answer.
- 4Unfolding nested structures10 minDecode-string style problems: a stack per nesting level, and the recursion it quietly replaces.
- 5Spotting stack problems8 minThe cues for plain and monotonic stacks, the increasing-or-decreasing decision, and the templates.
Practice it after
Real interview questions that test this pattern, in an editor with execution and AI feedback.