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Interview Prep

One ordered checklist for product / fintech interviews: DSA (Blind 75), LLD and HLD. Tick items off as you go; open Details for the optimal approach, complexity and how it is asked.

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Start here0/5

1.LLD study plan & how to use this seriesRead
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2.Java + DSA basics primer (Big-O, collections, concurrency, money is never a double)Read
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3.DSA patterns roadmap for beginners (which pattern to learn when)Read
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4.HLD fundamentals for beginnersRead
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5.Skim the Glossary tab (266 terms: QPS, CAS, idempotency, L7...)Read

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Array0/10

1.Two SumEasyLC 1
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2.Best Time to Buy and Sell StockEasyLC 121
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3.Contains DuplicateEasyLC 217
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4.Product of Array Except SelfMediumLC 238
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5.Maximum SubarrayMediumLC 53
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6.Maximum Product SubarrayMediumLC 152
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7.Find Minimum in Rotated Sorted ArrayMediumLC 153
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8.Search in Rotated Sorted ArrayMediumLC 33
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9.3SumMediumLC 15
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10.Container With Most WaterMediumLC 11
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Binary / Bit Manipulation0/5

1.Sum of Two IntegersMediumLC 371
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2.Number of 1 BitsEasyLC 191
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3.Counting BitsEasyLC 338
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4.Missing NumberEasyLC 268
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5.Reverse BitsEasyLC 190
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String0/10

1.Longest Substring Without Repeating CharactersMediumLC 3
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2.Longest Repeating Character ReplacementMediumLC 424
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3.Minimum Window SubstringHardLC 76
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4.Valid AnagramEasyLC 242
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5.Group AnagramsMediumLC 49
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6.Valid ParenthesesEasyLC 20
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7.Valid PalindromeEasyLC 125
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8.Longest Palindromic SubstringMediumLC 5
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9.Palindromic SubstringsMediumLC 647
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10.Encode and Decode StringsMediumLC 271
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Linked List0/6

1.Reverse Linked ListEasyLC 206
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2.Linked List CycleEasyLC 141
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3.Merge Two Sorted ListsEasyLC 21
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4.Merge k Sorted ListsHardLC 23
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5.Remove Nth Node From End of ListMediumLC 19
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6.Reorder ListMediumLC 143
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Tree, BST & Trie0/14

1.Maximum Depth of Binary TreeEasyLC 104
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2.Same TreeEasyLC 100
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3.Invert Binary TreeEasyLC 226
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4.Binary Tree Maximum Path SumHardLC 124
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5.Binary Tree Level Order TraversalMediumLC 102
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6.Serialize and Deserialize Binary TreeHardLC 297
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7.Subtree of Another TreeEasyLC 572
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8.Construct Binary Tree from Preorder and Inorder TraversalMediumLC 105
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9.Validate Binary Search TreeMediumLC 98
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10.Kth Smallest Element in a BSTMediumLC 230
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11.Lowest Common Ancestor of a BSTMediumLC 235
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12.Implement TrieMediumLC 208
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13.Design Add and Search Words Data StructureMediumLC 211
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14.Word Search IIHardLC 212
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Heap0/2

1.Top K Frequent ElementsMediumLC 347
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2.Find Median from Data StreamHardLC 295
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Interval0/5

1.Insert IntervalMediumLC 57
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2.Merge IntervalsMediumLC 56
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3.Non-overlapping IntervalsMediumLC 435
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4.Meeting RoomsEasyLC 252Premium
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5.Meeting Rooms IIMediumLC 253Premium
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Matrix0/4

1.Set Matrix ZeroesMedium
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2.Spiral MatrixMedium
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3.Rotate ImageMedium
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4.Word SearchMedium
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Graph0/8

1.Clone GraphMediumLC 133
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2.Course ScheduleMediumLC 207
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3.Pacific Atlantic Water FlowMediumLC 417
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4.Number of IslandsMediumLC 200
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5.Longest Consecutive SequenceMediumLC 128
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6.Alien DictionaryHardLC 269Premium
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7.Graph Valid TreeMediumLC 261Premium
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8.Number of Connected Components in an Undirected GraphMediumLC 323Premium
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Dynamic Programming0/11

1.Climbing StairsEasy
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2.Coin ChangeMedium
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3.Longest Increasing SubsequenceMedium
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4.Longest Common SubsequenceMedium
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5.Word BreakMedium
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6.Combination SumMedium
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7.House RobberMedium
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8.House Robber IIMedium
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9.Decode WaysMedium
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10.Unique PathsMedium
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11.Jump GameMedium
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Backend and AI engineer for financial products. Open to projects and one-off engagements.

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Pictures, all public domain via Wikimedia Commons: Map of the native town of Bombay, 1855 (Vacher & Sons); Luckett Ledger; Millinery Book Ledger (W. S. Clark); Bandra-Kurla complex Bombay 3239 (Nikhil Kulkarni).