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medium· trees Mock interview

Construct Binary Tree from Preorder and Inorder

Given `preorder` and `inorder` traversals of a binary tree with unique values, reconstruct and return the tree (its level-order form).

Examples

in: preorder = [3,9,20,15,7], inorder = [9,3,15,20,7]

out: [3,9,20,null,null,15,7]

the unique tree

Constraints

1 <= number of nodes <= 3000
values are unique
inorder is a permutation of preorder

Hints

target: O(n) time⌘↩ run · ⇧⌘↩ submit