Read the tells. Every pattern below starts with "How to spot it" — the structural clues hiding in a problem statement.
Match the trigger words. Phrases like sorted array, k largest or minimize the maximum give the pattern away instantly.
Recall the skeleton. Each pattern has one short Python template. Learn it once, adapt it everywhere.
Drill the problems. Solve the linked LeetCode problems and read why the pattern fires on each one.
Timed reps on traversal, in-place edits, rotation and string parsing fundamentals.
Pointer surgery practice — reversals, merges, cycle games and dummy-node tricks.
Monotonic stacks, deques and design problems built from LIFO and FIFO parts.
DFS, BFS, BST invariants and recursion-with-return-values, step by step.
Flood fill, topological sort, union-find and shortest-path adventures.
From recursive brute force to memoisation to tables — graded DP katas.
Top-k, streaming medians and scheduling problems with heaps.
Boundary templates, rotated arrays and searching the answer space.
XOR tricks, masks and counting bits without fear.