Top DSA coding patterns | Leetcode questions

1. Sliding Window

• https://leetcode.com/problems/longest-substring-without-repeating-characters/
• https://leetcode.com/problems/sliding-window-maximum/
• https://leetcode.com/problems/minimum-window-subsequence/
• https://leetcode.com/problems/repeated-dna-sequences/
• https://leetcode.com/problems/minimum-window-substring/
• https://leetcode.com/problems/minimum-size-subarray-sum/
• https://leetcode.com/problems/best-time-to-buy-and-sell-stock/
• https://leetcode.com/problems/find-all-anagrams-in-a-string/

2. Hash Maps

• https://leetcode.com/problems/design-hashmap/
• https://leetcode.com/problems/fraction-to-recurring-decimal/
• https://leetcode.com/problems/logger-rate-limiter/
• https://leetcode.com/problems/next-greater-element-i/
• https://leetcode.com/problems/isomorphic-strings/
• https://leetcode.com/problems/longest-palindrome/
• https://leetcode.com/problems/design-tic-tac-toe/
• https://leetcode.com/problems/contains-duplicate/
• https://leetcode.com/problems/two-sum/

3. Two Pointers

• https://leetcode.com/problems/valid-palindrome/
• https://leetcode.com/problems/3sum/
• https://leetcode.com/problems/reverse-words-in-a-string/
• https://leetcode.com/problems/valid-palindrome-ii/
• https://leetcode.com/problems/sort-list/ ( Linked List + Two pointers)
• https://leetcode.com/problems/container-with-most-water/
• https://leetcode.com/problems/linked-list-cycle-ii/ ( Linked List + Two pointers)

4 . Fast & Slow Pointers

• https://leetcode.com/problems/linked-list-cycle/
• https://leetcode.com/problems/happy-number/
• https://leetcode.com/problems/circular-array-loop/
• https://leetcode.com/problems/middle-of-the-linked-list/
• https://leetcode.com/problems/palindrome-linked-list/

5. Merge Intervals

• https://leetcode.com/problems/merge-intervals/
• https://leetcode.com/problems/insert-interval/
• https://leetcode.com/problems/interval-list-intersections/
• https://leetcode.com/problems/employee-free-time/
• https://leetcode.com/problems/meeting-rooms-ii/

6. Cyclic Sort

• https://leetcode.com/problems/missing-number/
• https://leetcode.com/problems/first-missing-positive/
• https://leetcode.com/problems/find-the-duplicate-number/
• https://www.geeksforgeeks.org/find-a-repeating-and-a-missing-number/
• https://www.geeksforgeeks.org/find-first-k-natural-numbers-missing-given-array/

7. In-place Reversal of a LinkedList

• https://leetcode.com/problems/reverse-linked-list/
• https://leetcode.com/problems/reverse-nodes-in-k-group/
• https://leetcode.com/problems/reverse-linked-list-ii/
• https://leetcode.com/problems/reorder-list/
• https://leetcode.com/problems/swapping-nodes-in-a-linked-list/
• https://leetcode.com/problems/reverse-nodes-in-even-length-groups/
• https://leetcode.com/problems/swap-nodes-in-pairs/

8. Graph Breadth-First Search

• https://leetcode.com/problems/pacific-atlantic-water-flow/ ( BFS/DFS)
• https://leetcode.com/problems/rotting-oranges/
• https://leetcode.com/problems/longest-increasing-path-in-a-matrix/ ( BFS/DFS + topological sort)

9. Graph Depth First Search

• https://leetcode.com/problems/shortest-bridge/ (DFS/BFS)
• https://leetcode.com/problems/number-of-connected-components-in-an-undirected-graph/ ( DFS/BFS/Union find)
• https://leetcode.com/problems/sum-of-distances-in-tree/ (DFS+ DP)
• https://leetcode.com/problems/reconstruct-itinerary/
• https://leetcode.com/problems/possible-bipartition/
• https://leetcode.com/problems/all-paths-from-source-to-target/ ( DFS+ Backtracking)

10. Heaps

• https://leetcode.com/problems/ipo/
• https://leetcode.com/problems/sliding-window-median/
• https://leetcode.com/problems/find-median-from-data-stream/
• https://leetcode.com/problems/task-scheduler/
• https://leetcode.com/problems/top-k-frequent-words/

11. Subsets

• https://leetcode.com/problems/subsets/
• https://leetcode.com/problems/permutations/
• https://leetcode.com/problems/letter-combinations-of-a-phone-number/
• https://leetcode.com/problems/generate-parentheses/
• https://leetcode.com/problems/partition-to-k-equal-sum-subsets/

12. Modified Binary Search

• https://leetcode.com/problems/search-in-rotated-sorted-array/
• https://leetcode.com/problems/first-bad-version/
• https://leetcode.com/problems/random-pick-with-weight/
• https://leetcode.com/problems/find-k-closest-elements/
• https://leetcode.com/problems/single-element-in-a-sorted-array/
• https://leetcode.com/problems/search-in-rotated-sorted-array-ii/

13. Bitwise Manipulation

• https://leetcode.com/problems/find-the-difference/
• https://leetcode.com/problems/complement-of-base-10-integer/
• https://leetcode.com/problems/flipping-an-image/
• https://leetcode.com/problems/single-number/
• https://leetcode.com/problems/single-number-ii/
• https://leetcode.com/problems/reverse-bits/

14. Top ‘K’ Elements

• https://leetcode.com/problems/kth-largest-element-in-a-stream/
• https://leetcode.com/problems/reorganize-string/
• https://leetcode.com/problems/k-closest-points-to-origin/
• https://leetcode.com/problems/top-k-frequent-elements/
• https://leetcode.com/problems/kth-largest-element-in-an-array/
• https://leetcode.com/problems/kth-smallest-element-in-a-bst/

15. K-way Merge

• https://leetcode.com/problems/merge-sorted-array/
• https://leetcode.com/problems/kth-smallest-element-in-a-sorted-matrix/
• https://leetcode.com/problems/find-k-pairs-with-smallest-sums/
• https://leetcode.com/problems/merge-k-sorted-lists/
• https://leetcode.com/problems/kth-smallest-element-in-a-sorted-matrix/
• https://leetcode.com/problems/median-of-two-sorted-arrays/

16. Tree Breadth-First Search

• https://leetcode.com/problems/binary-tree-level-order-traversal/
• https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal/
• https://leetcode.com/problems/populating-next-right-pointers-in-each-node/
• https://leetcode.com/problems/vertical-order-traversal-of-a-binary-tree/
• https://leetcode.com/problems/populating-next-right-pointers-in-each-node/

17. Tree Depth First Search

• https://leetcode.com/problems/flatten-binary-tree-to-linked-list/
• https://leetcode.com/problems/diameter-of-binary-tree/
• https://leetcode.com/problems/serialize-and-deserialize-binary-tree/
• https://leetcode.com/problems/invert-binary-tree/
• https://leetcode.com/problems/binary-tree-maximum-path-sum/
• https://leetcode.com/problems/maximum-depth-of-binary-tree/
• https://leetcode.com/problems/subtree-of-another-tree/
• https://leetcode.com/problems/same-tree/

18. Trie

• https://leetcode.com/problems/implement-trie-prefix-tree/
• https://leetcode.com/problems/search-suggestions-system/
• https://leetcode.com/problems/replace-words/
• https://leetcode.com/problems/design-add-and-search-words-data-structure/
• https://leetcode.com/problems/word-search-ii/
• https://leetcode.com/problems/lexicographical-numbers/

19. Topological Sort

• https://www.pepcoding.com/resources/online-java-foundation/graphs/compilation-order-official/ojquestion
• https://leetcode.com/problems/alien-dictionary/
• https://leetcode.com/problems/course-schedule/
• https://leetcode.com/problems/course-schedule-ii/
• https://leetcode.com/problems/find-all-possible-recipes-from-given-supplies/
• https://leetcode.com/problems/loud-and-rich/
• https://leetcode.com/problems/alien-dictionary/

20. Backtracking

• https://leetcode.com/problems/n-queens/
• https://leetcode.com/problems/word-search/
• https://leetcode.com/problems/house-robber-iii/
• https://leetcode.com/problems/restore-ip-addresses/
• https://leetcode.com/problems/sudoku-solver/
• https://leetcode.com/problems/matchsticks-to-square/
• https://leetcode.com/problems/permutations-ii/description/

21. Stack

• https://leetcode.com/problems/basic-calculator/
• https://leetcode.com/problems/remove-all-adjacent-duplicates-in-string/
• https://leetcode.com/problems/minimum-remove-to-make-valid-parentheses/
• https://leetcode.com/problems/exclusive-time-of-functions/
• https://leetcode.com/problems/flatten-nested-list-iterator/
• https://leetcode.com/problems/valid-parentheses/
• https://leetcode.com/problems/maximum-frequency-stack/
• https://leetcode.com/problems/largest-rectangle-in-histogram/
• https://leetcode.com/problems/evaluate-reverse-polish-notation/
• https://leetcode.com/problems/asteroid-collision/

22. Queue

• https://leetcode.com/problems/first-unique-character-in-a-string/
• https://leetcode.com/problems/implement-queue-using-stacks/
• https://leetcode.com/problems/implement-stack-using-queues/
• https://leetcode.com/problems/sliding-window-maximum/
• https://leetcode.com/problems/stamping-the-sequence/
• https://leetcode.com/problems/jump-game-vi/
• https://leetcode.com/problems/design-hit-counter/
• https://leetcode.com/problems/design-snake-game/
• https://leetcode.com/problems/minimum-number-of-k-consecutive-bit-flips/

23. Greedy

• https://leetcode.com/problems/jump-game/
• https://leetcode.com/problems/boats-to-save-people/
• https://leetcode.com/problems/gas-station/
• https://leetcode.com/problems/two-city-scheduling/
• https://leetcode.com/problems/jump-game-ii/
• https://leetcode.com/problems/non-overlapping-intervals/ ( Greedy + Dp)
• https://leetcode.com/problems/minimum-number-of-flips-to-make-the-binary-string-alternating/ ( Greedy + Dp)
• https://leetcode.com/problems/lemonade-change/

24. Dynamic Programming

• https://leetcode.com/problems/climbing-stairs/
• https://leetcode.com/problems/coin-change/
• https://practice.geeksforgeeks.org/problems/0-1-knapsack-problem0945/1
• https://leetcode.com/problems/n-th-tribonacci-number/
• https://leetcode.com/problems/partition-equal-subset-sum/
• https://leetcode.com/problems/word-break-ii/
• https://leetcode.com/problems/minimum-number-of-refueling-stops/
• https://leetcode.com/problems/longest-increasing-subsequence/
• https://leetcode.com/problems/unique-paths/
• https://leetcode.com/problems/longest-palindromic-subsequence/
• https://leetcode.com/problems/house-robber/

25. Union Find

• https://leetcode.com/problems/redundant-connection/
• https://leetcode.com/problems/number-of-islands/ ( Union Find / BFS/DFS)
• https://leetcode.com/problems/last-day-where-you-can-still-cross/
• https://leetcode.com/problems/regions-cut-by-slashes/
• https://leetcode.com/problems/minimize-malware-spread/
• https://leetcode.com/problems/number-of-provinces/
• https://leetcode.com/problems/most-stones-removed-with-same-row-or-column/

26. Custom Data structures

• https://leetcode.com/problems/lfu-cache/
• https://leetcode.com/problems/min-stack/
• https://leetcode.com/problems/insert-delete-getrandom-o1/
• https://leetcode.com/problems/lru-cache/
• https://leetcode.com/problems/time-based-key-value-store/
• https://leetcode.com/problems/snapshot-array/
• https://leetcode.com/problems/design-in-memory-file-system/
• https://leetcode.com/problems/design-file-system/

27. String

• https://leetcode.com/problems/palindrome-permutation/
• https://leetcode.com/problems/group-anagrams/
• https://leetcode.com/problems/first-unique-character-in-a-string/
• https://leetcode.com/problems/ransom-note/

28. Divide & Conquer

• https://leetcode.com/problems/maximum-subarray/
• https://leetcode.com/problems/number-of-1-bits/
• https://leetcode.com/problems/majority-element/

29. Binary Search

• https://leetcode.com/problems/find-minimum-in-rotated-sorted-array/

30. Sorting

• https://leetcode.com/problems/meeting-rooms/
• https://leetcode.com/problems/4sum/ ( Sorting + Two pointers)

31. Prefix sum

• https://leetcode.com/problems/product-of-array-except-self/

32. Djikstra Algorithm

• https://leetcode.com/problems/network-delay-time/ ( Djikstra/ Floyd / Bellman)
• https://leetcode.com/problems/cheapest-flights-within-k-stops/
• https://leetcode.com/problems/reachable-nodes-in-subdivided-graph/
• https://leetcode.com/problems/path-with-maximum-probability/
• https://leetcode.com/problems/minimum-cost-to-make-at-least-one-valid-path-in-a-grid/
• https://leetcode.com/problems/path-with-minimum-effort/ ( Djikstra/ Floyd / Bellman)
• https://leetcode.com/problems/number-of-restricted-paths-from-first-to-last-node/

33. Floyd Warshall

• https://leetcode.com/problems/evaluate-division/ (Floyd/ Union Find)
• https://leetcode.com/problems/cheapest-flights-within-k-stops/
• https://leetcode.com/problems/find-the-city-with-the-smallest-number-of-neighbors-at-a-threshold-distance/ ( Floyd/Djikstra)
• https://leetcode.com/problems/course-schedule-iv/
• https://leetcode.com/problems/number-of-ways-to-arrive-at-destination/

34. Bellman Ford

• https://leetcode.com/problems/cheapest-flights-within-k-stops/
• https://leetcode.com/problems/cat-and-mouse/
• https://leetcode.com/problems/get-watched-videos-by-your-friends/

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For reference coding questions under above categories:

1.) https://designgurus.org/course/grokking-the-coding-interview

2.) https://www.educative.io/courses/grokking-coding-interview-patterns-java

3.) https://leetcode.com/discuss/study-guide/1612475/all-leetcode-discuss-lists-and-my-lists-so-far-topic-wisedifficulty-wise

4.) https://www.geeksforgeeks.org/must-do-coding-questions-for-companies-like-amazon-microsoft-adobe/

5.) https://leetcode.com/list/xi4ci4ig/