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Given two binary trees and imagine that when you put one of them to cover the other, some nodes of the two trees are overlapped while the others are not.You need to merge them into a new binary tree. ...

Given a binary search tree and the lowest and highest boundaries as L and R, trim the tree so that all its elements lies in [L, R] (R >= L). You might need to change the root of the tree, so the re...

Given a non-empty binary tree, return the average value of the nodes on each level in the form of an array.Example 1:Input: 3 / \ 9 20 / \ 15 7Output: [3, 14.5, 11]Explanation:T...

Given a binary tree, return the preorder traversal of its nodes' values.For example:Given binary tree [1,null,2,3], 1 \ 2 / 3return [1,2,3]./** * Definition for a binary tree node....