Latest articles, tutorials, and deep dives from ndlab tech blog.
DP is not about memorizing problems. Recognize two signals — optimal substructure and overlapping subproblems — then apply 6 patterns that make DP finally approachable.
Every recursive solution is secretly a tree traversal. Once you see that, pruning becomes obvious. Master the backtracking template and 4 problem types found in every interview.
Sorting and binary search hide inside half your interview solutions. Master every sort variant, binary search on answer space, and the 3 patterns that turn O(n²) into O(n log n).
Graphs intimidate more than any other topic — but most problems use just 4 techniques. Master BFS, DFS, topological sort, and union-find with a clear decision framework.
Trees are the most-tested structure in FAANG interviews. Master DFS, BFS, all traversals, LCA, path sums, and BST validation with a recursive framework that makes it click.
Stacks feel easy until the interviewer asks for a queue using two stacks. Learn the monotonic stack, deque patterns, and the BFS connection that unlocks hard O(n) solutions.
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