DSA Patterns for Coding Interviews

Data structures and algorithms interviews reuse a small number of solution shapes. Thita.ai organises them into 16 DSA patterns and 99 subpatterns, each with theory, a curated problem list and AI-guided practice. 13 patterns cover what interviewers ask most often; the remaining 3 are depth patterns you reach for once the core set is solid. Working through every pattern takes roughly 45 hours of focused study.

All 16 DSA patterns

• Two Pointers — Master the two pointers technique including fast-slow pointers, converging pointers, and expanding from center. Essential for array, string, and linked list problems in coding interviews. 7 subpatterns, about 3 hours, interview-critical.
• Sliding Window — Master the sliding window technique for subarray and substring problems. Learn fixed size windows, variable size windows, and monotonic queue optimizations. 4 subpatterns, about 2.5 hours, interview-critical.
• Binary Search Patterns — Master binary search algorithms including standard search, rotated array search, search on answer space, and finding boundaries. Essential for efficient O(log n) solutions. 5 subpatterns, about 2.5 hours, interview-critical.
• Array/Matrix Manipulation Patterns — Master array and matrix manipulation techniques including in-place rotation, spiral traversal, prefix/suffix products, and cyclic sort. Essential patterns for coding interviews at FAANG companies. 10 subpatterns, about 4 hours, interview-critical.
• Linked List Manipulation Patterns — Master linked list manipulation including in-place reversal, merging sorted lists, detecting intersections, and reordering. Essential pointer manipulation techniques for interviews. 5 subpatterns, about 2 hours, interview-critical.
• Stack Patterns — Master stack-based algorithms including valid parentheses, monotonic stack for next greater element, expression evaluation, and histogram problems. 6 subpatterns, about 2.5 hours, interview-critical.
• String Manipulation Patterns — Master string manipulation including palindrome checking, anagram detection, string matching algorithms (KMP, Rabin-Karp), and conversion problems. 6 subpatterns, about 2 hours, interview-critical.
• Tree Traversal Patterns (DFS & BFS) — Master tree traversal including preorder, inorder, postorder DFS, level order BFS, lowest common ancestor, and tree serialization techniques. 6 subpatterns, about 3 hours, interview-critical.
• Heap (Priority Queue) Patterns — Master heap-based algorithms including top K elements, two heaps for median, K-way merge, and scheduling problems with priority queues. 4 subpatterns, about 2 hours, interview-critical.
• Greedy Patterns — Master greedy algorithms including interval scheduling, jump games, stock trading, and task scheduling. Make locally optimal choices for global optimization. 7 subpatterns, about 3 hours, interview-critical.
• Backtracking Patterns — Master backtracking algorithms including subsets, permutations, combinations, N-Queens, and word search. Exhaustive search with pruning for constraint satisfaction. 7 subpatterns, about 3 hours, interview-critical.
• Dynamic Programming (DP) Patterns — Master DP patterns including Fibonacci, Kadane, knapsack, LCS, LIS, edit distance, and grid paths. Solve optimization problems with overlapping subproblems. 12 subpatterns, about 5 hours, interview-critical.
• Graph Traversal Patterns (DFS & BFS) — Master graph algorithms including DFS/BFS traversal, topological sort, shortest paths (Dijkstra, Bellman-Ford), Union-Find, and advanced graph concepts. 12 subpatterns, about 5 hours, interview-critical.
• Bit Manipulation Patterns — Master bit manipulation including XOR tricks, counting bits, power of two checks, and bit masking. Essential for optimization and low-level problems. 4 subpatterns, about 1.5 hours, depth mastery.
• Design Patterns — Master data structure design including LRU/LFU cache, Trie, Min Stack, and system design problems. Implement efficient data structures for interviews. 2 subpatterns, about 1.5 hours, depth mastery.
• Segment Tree & Fenwick Tree Patterns — Master advanced data structures for range queries and point updates. Learn Fenwick Tree (Binary Indexed Tree) for prefix queries and Segment Tree for range sum operations. 2 subpatterns, about 2 hours, depth mastery.

How the DSA pattern course works

Each pattern page lists its subpatterns in the order they build on one another, with the techniques the pattern relies on and the problems that drill them. Start at the top of a pattern, read the theory for a subpattern, then solve its problems in the editor with the AI coach available for a hint rather than a finished answer. Progress is tracked per subpattern, so you can see which parts of a pattern you have covered and which still need work.

Where to go next

• Looking for the practice sheet? The DSA patterns sheet tracks progress against the same 16 patterns as a single checklist of problems, with company tags.
• Coding practice — browse and solve the problems themselves, run them and submit in the editor.
• System design patterns — the high-level design track.
• Low-level design patterns — the object-oriented design track.