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§ cs 302 · 7 guides

CS 302 — Coding Patterns

Two pointers, sliding window, prefix sum, monotonic stack/deque, intervals — the recurring problem shapes that show up across the interview catalog.

Level
7 guides
# Code Name Level Updated
1 —
Fast & Slow Pointers Two pointers moving at different speeds — Floyd's cycle detection and middle-of-list tricks.
beginner
2 —
Merge Intervals Sort by start, then sweep — the answer to most "schedules / overlaps" problems.
beginner
3 —
Monotonic Deque Deque that stays sorted — sliding window max/min in O(n).
intermediate
4 —
Monotonic Stack Stack that stays sorted — solves "next greater element" and histogram problems in O(n).
intermediate
5 —
Prefix Sum Precompute cumulative sums to answer range-sum and subarray-target queries in O(1).
beginner
6 —
Sliding Window Maintain a moving range over a sequence to answer every-subarray-of-size-k questions in O(n).
beginner
7 —
Two Pointers Walk a sequence with two indices to collapse O(n²) brute force into O(n).
beginner