intermediate

Monotonic Stacks & Queues

Maintain candidates in monotonic order so dominated values disappear permanently in boundary, histogram, and range-extrema problems.

Problems

Problems in Monotonic Stacks & Queues

Practice problems that share this primary solution pattern and compare the clues that reveal it.

advanced

13 min read

The hard part is rarely choosing a rectangle height. It is proving how far that height can extend.

expert

12 min read

Turn each matrix row into a histogram, solve that histogram with a monotonic stack, and keep only the state that can still affect future rows.