dsa5 min read
Range Sum of BST — LeetCode 938 BST Pruning DFS
LeetCode 938 — Range Sum of BST, asked at Amazon, Facebook (Meta), Google and Apple. Use the BST property to prune entire out-of-range subtrees and run in O(h + k) time.
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Bst
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dsa5 min read
Search in a Binary Search Tree — LeetCode 700 BST Property in O(h)
LeetCode 700 — Search in a BST, asked at Amazon, Microsoft, Apple and Meta. Eliminate half the tree at each step using the BST property and finish in O(h) time, O(1) iterative space.
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dsa5 min read
Delete Node in a BST — LC 450 Interview Deep Dive
LC 450 Delete Node in a BST is a top FAANG interview problem testing all three deletion cases. Master the in-order successor strategy to pass BST questions at Amazon, Google, and Microsoft.
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dsa5 min read
Convert BST to Greater Tree — LC 538 Reverse In-Order Pattern
Solve LeetCode 538 Convert BST to Greater Tree using reverse in-order traversal asked at Google, Microsoft, and Amazon. Single O(n) pass with O(h) space.
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dsa5 min read
Trim a Binary Search Tree — LC 669 Recursive Pruning
Trim a BST so all values lie within [low, high] using recursive subtree pruning. LeetCode 669 is a Medium FAANG question asked at Amazon, Google, and Apple.
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dsa5 min read
Serialize and Deserialize BST — LC 449 Compact Preorder
Encode a BST compactly using preorder traversal without null markers and rebuild it with min-max bounds. LeetCode 449 is a Medium FAANG question asked at Amazon, Google, and Meta.
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dsa5 min read
Recover Binary Search Tree — LC 99 In-Order Inversion Trick
Recover a BST where two nodes are swapped using in-order traversal to find the inversion pair. LeetCode 99 is asked at Amazon, Google, and Meta. Includes O(1) space Morris traversal solution.
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dsa6 min read
Maximum Sum BST in Binary Tree — LC 1373 Post-Order Metadata
LC 1373 Maximum Sum BST in Binary Tree finds the highest sum among all BST subtrees of a binary tree. The O(n) solution uses post-order DFS returning a 4-tuple of (is_bst, min, max, sum) metadata — a hard FAANG problem tested at Amazon and Google.
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dsa6 min read
Construct BST from Preorder Traversal — LC 1008 Bounds-Based O(n)
LC 1008 Construct BST from Preorder Traversal reconstructs a binary search tree in O(n) using min-max bounds to decide left vs right placement — a clean recursion problem tested at Amazon and Google that showcases BST property exploitation.
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dsa5 min read
Inorder Successor in BST II — With Parent Pointers in O(h)
LeetCode 510 (Medium) frequently asked at Microsoft and Facebook. Find the inorder successor of a BST node when each node has a parent pointer, in O(h) time and O(1) extra space without access to the root.
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dsa5 min read
Insert into a Binary Search Tree — LC 701 Recursive and Iterative
LC 701 Insert into a BST traverses left or right based on value comparisons until finding a null position. The O(h) recursive solution is a BST fundamentals question tested at Amazon and Microsoft — always insert at a leaf.
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dsa4 min read
Increasing Order Search Tree — LeetCode 897 Inorder Rewire in O(n)
LeetCode 897 (Easy). Rebuild a BST into a strictly right-skewed list using a single inorder traversal that rewires left and right pointers in place.
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