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72. Make a Binary Tree from Given Inorder and Preorder Traversal

Objective: - Given a inorder and preorder traversal, construct a binary tree from that.

Input: Inorder and preorder traversals

Similar Problem: Construct a binary tree from given Inorder and Postorder Traversal


int [] inOrder = {2,5,6,10,12,14,15};

int [] preOrder = {10,5,2,6,14,12,15};

  • First element in preorder[] will be the root of the tree, here its 10.
  • Now the search element 10 in inorder[], say you find it at position i, once you find it, make note of elements which are left to i (this will construct the leftsubtree) and elements which are right to i ( this will construct the rightSubtree).
  • See this step above and recursively construct left subtree and link it root.left and recursively construct right subtree and link it root.right.
  • See the picture and code.


Constructed Tree :
  2  5  6  10  12  14  15