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Week 3Day 21 of 35

Week 3 Review

Reinforce stack thinking and binary-search pattern recognition before moving on.

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0 of 6 problems solved

Pattern Focus

Week 3 Review

Reinforce stack thinking and binary-search pattern recognition before moving on.

Pattern Checklist
  • Can I tell when LIFO solves the problem?
  • Can I tell when binary search can cut the problem in half?
  • Can I explain why the chosen pattern fits before coding?
🧭New to DSA? Start here 🧠

Week three is about recognizing whether the problem cares about the most recent unfinished thing or about deleting half the search space. If it is about unfinished structure, think stack. If sorted order lets you throw away half the candidates, think binary search. Review day is really a pattern sorting exercise in your own head.

The two big questions are: am I resolving the latest thing, or am I cutting the search space in half?

How to think about it
  1. 1Ask whether the problem needs last-in-first-out behavior.
  2. 2If yes, think stack and unresolved state.
  3. 3If not, ask whether sorted order lets you eliminate half the candidates.
  4. 4If yes, think binary search or a rotated-array variation.
🚧Common Mistake

Mixing stack problems and binary-search problems usually happens when you focus on the data instead of the question the algorithm is answering.

Problems

Review: Valid Parentheses

easy

Review: Daily Temperatures

medium

Review: Binary Search

easy

Review: Search in Rotated Sorted Array

medium

Review: Find Minimum in Rotated Sorted Array

medium

Review: Evaluate Reverse Polish Notation

medium