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Week 1Day 7 of 35

Week 1 Review

Reinforce HashMap and Two Pointers until pattern recognition feels natural.

Day Progress0%

0 of 12 problems solved

Pattern Focus

Week 1 Review

Reinforce HashMap and Two Pointers until pattern recognition feels natural.

Pattern Checklist
  • Can I name the pattern before writing code?
  • Would HashMap or Two Pointers solve this faster?
  • Do I know why the pattern fits?
🧭New to DSA? Start here 🧠

The goal of review day is not to memorize code line by line. It is to notice the shape of a problem. Need to remember what you have seen? That smells like a HashMap. Comparing two ends at once? That is a two-pointer problem. Tracking the cheapest point before a later profit? That is the stock pattern from day two. Once you can name the pattern before you touch the keyboard, the solution becomes much easier to build.

Beginners usually focus on syntax. Strong problem solvers focus on pattern recognition first.

How to think about it
  1. 1Read the prompt and ask what the problem wants you to remember or compare.
  2. 2If you need fast memory of past values, think HashMap.
  3. 3If the answer depends on the left and right sides together, think two pointers.
  4. 4If the array is sorted, ask how that order helps you move more intelligently.
  5. 5Before coding, say the pattern out loud. If you can name it, you can usually build it.
🚧Common Mistake

Trying to memorize exact code templates before recognizing the pattern usually makes review day feel harder than it should.

Problems

Review: Two Sum

easy

Review: Best Time to Buy and Sell Stock

easy

Review: Valid Palindrome

easy

Review: Two Sum II

easy

Review: Container With Most Water

medium

Review: 3Sum

medium

Extra: Contains Duplicate

easy

Extra: Valid Anagram

easy

Extra: Move Zeroes

easy

Extra: Remove Duplicates from Sorted Array

easy

Extra: Group Anagrams

medium

Extra: Trapping Rain Water

hard