Learning Resources
Learn
The sheets tell you what to solve. These tell you how the thing works — one guide per topic, written to be read once and then used as a reference, not one thin page per question.
Tracks3
DSA Patterns
The recurring shapes behind interview problems — what each pattern is, when it applies, the template that solves it, and the mistakes that cost people the round.
22/22 written
SQL
Query topics as they actually come up in interviews — joins, window functions, CTEs and the analytics patterns built on them, each with runnable queries.
16/40 written
System Design
Design problems worked end to end: requirements, back-of-envelope numbers, the architecture, and the trade-offs an interviewer will push on.
32/32 written
Latest6
Backtracking
DSA Patterns · 3 minChoose, recurse, un-choose. One template generates every subset, permutation and combination — pruning is what makes it fast.
Breadth First Search (BFS)
DSA Patterns · 3 minA queue, a visited set, and level-by-level expansion — the shortest path on any unweighted graph.
Bitwise XOR
DSA Patterns · 4 minFour algebraic properties turn 'find the unpaired number' into a one-line O(1)-space scan.
Cyclic Sort (Index-Based)
DSA Patterns · 3 minWhen the values are 1..n, the array is its own hash map — swap each value home and read off what is missing.
Design Data Structure
DSA Patterns · 3 minEvery answer is two structures combined — a hash map for lookup plus something that maintains order.
Depth First Search (DFS)
DSA Patterns · 3 minGo deep, backtrack, repeat — the pattern behind islands, flood fill, and every connectivity question.