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12+ curated questions with the same answer shape every time: quick recap, deep dive, pitfalls, and follow-ups. Coverage includes bfs traversal, graph representations.
Suggested path
Topics follow a teaching order. Each answer ends with a clear Next question control so you can move forward without hunting the list.
Graph questions at the fresher level are almost always disguised matrix problems — number of islands, flood fill, course schedule (cycle detection), and word ladder. The underlying technique is always BFS or DFS with a visited set. This module teaches the template for each traversal, when to pick BFS (shortest path, level-by-level) vs DFS (cycle detection, path exploration), and the adjacency-list vs adjacency-matrix representation trade-off. Mastering graphs at this level means being able to recognise a graph problem that is dressed up as a 2D grid.
Full catalog
Topics are ordered for learning. Within each topic, rows are numbered 1–12 globally so you always know where you are. Collapse topics if you want a lighter view — use Expand all when you need the full list again.
Numbers 1–12 follow the order we recommend — click any row to open the full answer, or use the sticky Next link at the bottom of each page to go Q1 → Q12.