Construct Binary Tree from Preorder and Inorder Traversal (Java)

LeetCode

Given preorder and inorder traversal of a tree, construct the binary tree.

Note:
You may assume that duplicates do not exist in the tree.

Solution: Divide and Conquer

According to the rule of preorder traversal,  the first item in the preorder array must be the root. and the question also told us "You may assume that duplicates do not exist in the tree." so we can go through inorder array find the root's position, then  we got left tree and right tree. finally we can apply recursion to got the tree we want base on above logic.