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N-ary Tree Level Order Traversal — LeetCode 429 BFS Pattern
LeetCode 429 N-ary Tree Level Order Traversal is a level-by-level BFS over a tree where each node has any number of children. Common at Amazon and Meta as a BFS warmup.
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Binary Tree Pruning — LeetCode 814 Post-Order Recursion
LeetCode 814 Binary Tree Pruning removes every subtree that contains no 1. Solve it in O(n) using post-order recursion — a classic Amazon and Google interview question.
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dsa5 min read
Maximum Level Sum of a Binary Tree — LeetCode 1161 BFS Pattern
LeetCode 1161 Maximum Level Sum returns the smallest level whose node-sum is largest. Solve in O(n) with BFS level-size snapshots — a common Amazon and Meta phone-screen question.
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Smallest String Starting From Leaf — LeetCode 988 DFS Pattern
LeetCode 988 Smallest String Starting From Leaf returns the lexicographically smallest leaf-to-root string. Solve in O(n * h) using DFS with path strings — popular at Amazon and Google.
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Amount of Time for Binary Tree to Be Infected — LeetCode 2385 Multi-Source BFS
LeetCode 2385 Amount of Time for Binary Tree to Be Infected models tree-to-graph BFS spread. Solve in O(n) by converting to an undirected graph and running BFS from the start node — common at Amazon, Google, and Meta.
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