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Leetcode 173. Binary Search Tree Iterator
Implement an iterator over a BST that returns elements in in-order (ascending) via next() and hasNext(), starting before the smallest element so the first next() yields the minimum. Aim for next()/hasNext() to handle up to 1e5 calls with amortized O(1) time and O(h) extra space (h = tree height).
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Early December, 2025
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Senior
You have a binary tree, you need to implement a iterator which returns a single element, traversing tree in in-order. https://leetcode.com/problems/binary-search-tree-iterator
Early October, 2025
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Mid-level
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