GuideTechnology
18 min read
A realistic week-by-week plan for working through this course around college or a job: what to learn, implement, practise and revise each week, with timed sessions, mock interviews, a spaced-revision schedule, and lighter and more intensive alternatives.
GuideTechnology
24 min read
Build a small, complete Java project that uses many data structures together: a practice tracker with spaced-repetition reviews, undo, title autocomplete and a prerequisite-based study order. Requirements, design, milestones, test cases and extension ideas, with no paid services.
GuideTechnology
23 min read
A step-by-step routine for coding interviews: clarify, work examples, state a brute force, optimize, agree on a plan, code, test and analyze. Includes a full sample dialogue, advice on getting unstuck, and checklists you can use in mock interviews.
GuideTechnology
22 min read
What to do when prefix sums are not enough: Fenwick and segment trees for range queries with updates (optional depth), and disjoint set union with path compression and union by size for connectivity, cycles and Kruskal's algorithm (the part worth knowing).
GuideTechnology
19 min read
A trie stores words so that shared prefixes share nodes, making insert, exact search and prefix search take time proportional to the word length. Build one in Java, compare array and map nodes, and use it for autocomplete, wildcards and shortest-prefix replacement.
GuideTechnology
21 min read
Apply the six-step DP workflow to climbing stairs, house robber, grid paths and the longest common subsequence. For each: state, transition, base cases, evaluation order, complexity and why it is correct, with full tables and reconstruction.
GuideTechnology
20 min read
Dynamic programming is recursion that remembers. Learn overlapping subproblems and optimal substructure, memoization and tabulation on Fibonacci, a repeatable six-step formulation workflow, and the coin change problem that greedy cannot solve.
GuideTechnology
24 min read
When BFS is enough and when it is not, Dijkstra's algorithm with a priority queue and its non-negative-weight limit, a glance at Bellman-Ford, and topological sorting with Kahn's algorithm and DFS for dependency order, including how to detect impossible orders.
GuideTechnology
24 min read
Vertices and edges, adjacency lists versus matrices, breadth-first and depth-first search, connected components, grids as graphs, and basic cycle detection in undirected and directed graphs, with complexity in terms of V and E.
GuideTechnology
20 min read
Binary numbers, the bitwise operators and Java's signed-integer behaviour, then the reasoned uses: parity, powers of two, counting bits, XOR, masks and subsets, plus GCD, modular arithmetic, fast exponentiation and the sieve of Eratosthenes.
GuideTechnology
22 min read
When picking the best-looking option at every step is actually correct, and when it is not. Learn to justify a greedy strategy, hunt for counterexamples, and solve activity selection, merge intervals, meeting rooms and jump game.
GuideTechnology
19 min read
Answer range-sum queries in constant time with a running-total array, count subarrays with a given sum using a hash map, compute product-except-self, handle 2D regions, and apply many range updates at once with a difference array.
GuideTechnology
18 min read
Fixed-size and variable-size windows over arrays and strings, with running sums, counters and frequency maps. Learn the expand-and-shrink template, why it runs in O(n), and when negative numbers break it.
GuideTechnology
18 min read
Replace nested loops with two indices that move in a controlled way. Learn the opposite-ends and same-direction patterns, why each pointer move is safe, and solve pair sum, container with most water, 3Sum and in-place deduplication.
GuideTechnology
22 min read
Linear and binary search done right (invariants, boundaries and overflow-safe midpoints), lower and upper bound, searching on the answer, the main sorting algorithms and their trade-offs, and how to sort anything in Java with comparators.
GuideTechnology
21 min read
How a heap keeps the smallest or largest item ready in O(1), how insert and remove work in O(log n), how to use Java's PriorityQueue, and how to solve top-K, k-th largest and merge-k-sorted problems. Includes how a heap differs from a BST.
GuideTechnology
22 min read
Tree vocabulary, the four traversals (preorder, inorder, postorder, level-order), recursive and iterative code, and binary search trees: search, insert, and the right way to validate one.
GuideTechnology
24 min read
Learn to think recursively: base cases, the call stack and recursion trees. Then use backtracking (choose, explore, undo) to generate subsets, permutations and combinations, avoid duplicates, prune the search and solve N-Queens.
GuideTechnology
20 min read
How hash tables find things almost instantly, what collisions are, how to use HashMap and HashSet in Java, and the patterns that solve duplicates, two-sum, grouping and counting problems. Includes the equals and hashCode contract.
GuideTechnology
19 min read
Last-in-first-out and first-in-first-out, explained with real examples. Learn the right Java collections (ArrayDeque, not Stack), then solve bracket matching, round-robin scheduling and next-greater-element with a monotonic stack.
GuideTechnology
20 min read
Build singly and doubly linked lists from scratch in Java, learn to reason about pointer changes step by step, and solve reversal, middle-finding, merging and cycle detection with clear diagrams and dry runs.
GuideTechnology
17 min read
How Java strings really work: characters and codes, comparison, immutability and StringBuilder, then the classic problems (palindromes, anagrams, run-length encoding) plus honest notes on Unicode.
GuideTechnology
20 min read
How arrays work in memory, why indexing is instant but inserting is slow, and how to solve the classic array problems: maximum, frequency counting, in-place rotation, moving zeroes and subarray sums.
GuideTechnology
19 min read
Big O explained by counting steps: constant, logarithmic, linear, n log n, quadratic and exponential growth, best, average and worst cases, auxiliary and recursion-stack space, with dry runs you can check yourself.
GuideTechnology
21 min read
Only the Java you need for data structures and algorithms: types and overflow, loops, methods, arrays, strings, a small class, input and output, and the mistakes that trip up almost every beginner.
GuideTechnology
17 min read
How to turn a vague problem statement into a clear plan: pin down inputs, outputs and constraints, list edge cases, write pseudocode, build a brute-force answer first and then improve it.
GuideTechnology
15 min read
What data structures and algorithms are, why employers test them, what you can honestly expect from this free 28-article course, and the repeatable six-step loop you will use on every problem.
CourseTechnology
28 lessons · 9 h
A free, 28-article course that takes you from basic problem solving to independently approaching common interview problems in Java. It explains each idea first, shows it in code you can run, and ends with exercises, solutions, an interview workflow and a study plan.
GuideTravel
7 min read
Travelling alone can be freeing and entirely safe with preparation. Here is how to plan, choose stays and transport, handle money and strangers, trust your instincts and what to do if something goes wrong.
GuideTravel
7 min read
A good trip doesn't need a huge budget. Here is how to choose a destination and season, estimate costs, book smartly, find cheap stays and food, and avoid the common tourist traps.
