From the pre-order array, we know that first element is the root.

We can find the root in in-order array. Then we can identify the left and right sub-trees of the root from in-order array.

Using the length of left sub-tree, we can identify left and right sub-trees in pre-order array. Recursively, we can build up the tree.

For this example, the constructed tree is: Since we are partitioning the left half and right half in sub function binary search tree traversal in c program. LeetCode — Construct Binary Tree from Preorder and Inorder Traversal Java. Given preorder and inorder traversal of a tree, construct binary search tree traversal in c program binary tree.

data structures - When to use Preorder, Postorder, and Inorder Binary Search Tree Traversal strategies - Stack Overflow

Analysis Consider the following example: You may also like Construct Binary Tree from Inorder and Postorder Traversal Leetcode — Binary Tree Inorder Traversal Java Leetcode — Binary Tree Preorder Traversal Java LeetCode — Binary Tree Level Order Traversal Java.

Binary search will only for in Binary Search tree not in binary tree. I would rather use binary search instead of using hashmap which costing space.