105. Construct Binary Tree from Preorder and Inorder Traversal

Given two integer arrays preorder and inorder where preorder is the preorder traversal of a binary tree and inorder is the inorder traversal of the same tree, construct and return the binary tree.


Note: I was using len(inorder) as initial call instead of len(inorder) - 1.
Use hashmap for looking up node in inorder.
I initially missed the recursion base condition termination start > end


def buildTree(self, preorder: List[int], inorder: List[int]):
   
    self.rootIndex = 0
   
    def recurse (start, end):
       
        if start > end:
            return None
       
        root = TreeNode(preorder[self.rootIndex])
        self.rootIndex += 1                
               
        root.left = recurse(start, inorder_index_map[root.val] - 1)
        root.right = recurse(inorder_index_map[root.val] + 1, end)
       
        return root
   
    inorder_index_map = {}
    for index, value in enumerate(inorder):
        inorder_index_map[value] = index
   
    return recurse(0, len(inorder)-1)

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