OS practice: Banker's algorithm with 6 solved problems, safe sequences and deadlock detection: https://techvaniai.blogspot.com/2026/10/bankers-algorithm-and-deadlock-6-solved.html

DBMS practice: BCNF vs 3NF with 6 solved problems on decomposition and dependency preservation: https://techvaniai.blogspot.com/2026/10/bcnf-vs-3nf-6-solved-problems-on.html

CN practice: TCP and sliding window with 6 solved problems on utilization and congestion control: https://techvaniai.blogspot.com/2026/10/tcp-and-sliding-window-numericals-6.html

DSA practice: time complexity with 6 solved loop and recurrence problems, including the Master theorem: https://techvaniai.blogspot.com/2026/10/time-complexity-questions-6-solved-loop.html

COA practice: cache memory with 6 solved problems on address bits, hit ratio, AMAT and a hit-miss trace https://techvaniai.blogspot.com/2026/10/cache-memory-numericals-6-solved.html

Compiler Design practice: FIRST and FOLLOW with 6 solved problems and LL(1) parsing tables https://techvaniai.blogspot.com/2026/10/compiler-design-first-follow-ll1-solved.html

DSA Episode 2: linear, sentinel and binary search plus bubble, selection and insertion sort with traced examples https://techvaniai.blogspot.com/2026/10/dsa-02-searching-bubble-selection-insertion-sort.html

DSA Episode 3: merge sort, quick sort, counting sort and radix sort with traced examples and counted comparisons https://techvaniai.blogspot.com/2026/10/dsa-03-merge-quick-counting-radix-sort.html

Postfix trap: 20 5 / 3 - = 1. Pop the right operand first, then the left: 20/5 = 4, then 4-3 = 1. DSA Ep4 has tested stack and circular-queue traces plus practice answers: https://techvaniai.blogspot.com/2026/10/dsa-04-stack-postfix-evaluation-circular-queue.html

BST deletion trap: deleting 40 from keys 40,20,60,10,30,50,70 uses successor 50, not 60. Inorder afterward is 10,20,30,50,60,70. DSA Ep6: trees, BST, AVL and LCA. Tested code and practice: https://techvaniai.blogspot.com/2026/10/dsa-06-trees-bst-avl-rotations-lca.html

Heap trap: [5,10,30,20,15] is a valid min-heap, not a sorted array. Removing 5 gives [10,15,30,20]. DSA Ep7 covers heaps, priority queues and hash collisions with tested code and practice: https://techvaniai.blogspot.com/2026/10/dsa-in-30-days-episode-7-heaps-priority.html

Graph trap: BFS finds the fewest edges, not the cheapest weighted route. DSA Ep8 covers BFS, DFS, Dijkstra, MST and topological sorting with tested traces and practice: https://techvaniai.blogspot.com/2026/10/dsa-in-30-days-episode-8-graphs-bfs-dfs.html

Coin-change trap: with coins 1,3,4 and amount6, greedy picks4+1+1 (3coins), but3+3 needs2. DSA Ep9 explains greedy vs dynamic programming with tested code and practice: https://techvaniai.blogspot.com/2026/10/dsa-in-30-days-episode-9-greedy-and.html

Backtracking trap: saving path itself keeps one shared list; path.copy() saves each answer before undo. DSA Ep10 has tested subsets, permutations, N-Queens and the final revision sheet:https://techvaniai.blogspot.com/2026/10/dsa-in-30-days-episode-10-backtracking-revision.html

Python exception trap: an error raised in else is not caught by the preceding except. Keep the operation you intend to protect in try, and success-only work in else. Eight tested examples cover handlers, cleanup, return and re-raise, with exact outputs and exam answers: https://techvaniai.blogspot.com/2026/10/python-try-except-else-finally-8-tested.html

New on YouTube: DSA Episode 3 (about 20 min, Hinglish) covers merge sort, quick sort, counting sort and radix sort with traced examples. Watch: https://youtu.be/KGD8c44ZmmI Notes and Python lab: https://techvaniai.blogspot.com/2026/10/dsa-03-merge-quick-counting-radix-sort.html

Python generator trap: sum consumes a generator, so a second sum on the same exhausted object returns 0. Create a fresh generator for another pass. Eight tested examples explain iterators, yield, lazy pipelines and bounded infinite streams, with exact outputs and practice answers: https://techvaniai.blogspot.com/2026/10/python-iterators-generators-yield-lazy-8-tested.html

Python groupby trap: A A B A makes three adjacent groups, not two global groups. Sort on the same key only when changing the original order fits your task. Eight tested examples explain groupby, accumulate, pairwise, islice and tee, with exact outputs and practice answers: https://techvaniai.blogspot.com/2026/10/python-itertools-groupby-accumulate-8-tested.html

Python sorting trap: values.sort() changes the list but returns None. Use sorted(values) when you need a new list. Eight tested examples explain keys, stable ties, mixed sort directions, missing values and dictionary sorting, with exact outputs and practice answers: https://techvaniai.blogspot.com/2026/10/python-sorted-list-sort-keys-stability-8-tested.html

Python dict/set trap: membership in a dict checks keys, not values. A set removes duplicates but does not guarantee insertion order; dict.fromkeys keeps first appearance. Eight tested examples cover lookup, word counts, set operations, hashable keys and ordering, with exact outputs and practice answers: https://techvaniai.blogspot.com/2026/10/python-dict-vs-set-lookup-deduplication-8-tested.html