Week 1: Foundation Patterns

Week $1$ focuses on the highest-frequency patterns:

$1.$ Day $1$: Hash Map ($5$ problems). Work on frequency counting patterns.

$2.$ Day $2$: Two Pointers ($5$ problems). Focus on sorted array techniques.

$3.$ Day $3$: Sliding Window ($5$ problems). Practice variable and fixed windows.

$4.$ Day $4$: Prefix Sum ($4$ problems). Build cumulative sum intuition.

$5.$ Day $5$: Stack ($5$ problems). Focus on parentheses and monotonic patterns.

$6.$ Day $6$: Review. Redo any problems you couldn't solve without hints.

Day $7$ is rest. Don't skip it.