DSA pattern
Stack
Stacks follow Last-In-First-Out (LIFO) order, making them perfect for problems where the most recent element matters most. Monotonic stacks maintain elements in sorted order for "next greater/smaller element" problems.
When to use
5 signals- 01Matching brackets and parentheses
- 02Next greater/smaller element
- 03Evaluating expressions (postfix, infix)
- 04Tracking state during recursion
- 05Histogram problems
In interviews, call out the pattern early. It helps interviewers follow your reasoning and keeps your implementation focused. After solving, explain tradeoffs in plain language: why this approach is efficient, where it can break, and what edge cases you would test first.
Practice problems
4 listed- 01Valid ParenthesesPractice →
- 02Daily TemperaturesPractice →
- 03Largest Rectangle in HistogramPractice →
- 04Evaluate RPNPractice →
Build a review loop
Treat each pattern as a repeating cycle, not a one-time read. Solve a fresh problem today, revisit the same pattern in 2-3 days, and run one timed attempt at the end of the week. This turns short-term familiarity into reliable recall for live interviews.
When reviewing, re-derive the core steps from scratch before checking a reference solution. If you can explain the state transitions and edge cases clearly, you are much more likely to execute well under interview pressure.