Medium · Streams & I/O
Binary tree in-order iterator
Given the root of a binary tree, build an iterator whose next() returns the tree's values in in-order (left subtree, node, right subtree), one per call, and whose hasNext() reports whether any value remains.
Examples
Example 1
[1,2,3,4,5,6,7]Output: [4, 2, 5, 1, 6, 3, 7]
Example 2
[4,2,6,1,3,5,7]Output: [1, 2, 3, 4, 5, 6, 7]
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