Find the Distance between Two Nodes of a Binary Tree.

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Objective: – Given nodes in a binary tree, find the distance between them.

Example :

Distance-between-two-nodes-example

Approach:

  • Distance(X, Y) = Distance(root, X) +Distance(root, Y) – 2*(Distance(root to LCA(X,Y)
  • where LCA(X,Y) = Lowest Common Ancestor of X,Y
  • In the above example if Distance(20,45) = 3
  • Distance(root, 20) = 2
  • Distance(root, 45) = 3
  • LCA(20, 45) = 10
  • Distance(root, 10) = 1
  • Distance(20,45) = 2+3 – 2*1 = 3

Now problem is reduced to How to find distance from root to any given node and How to find Lowest Common Ancestor of two given nodes.

Complete Code:


Output:

Distance between 45 and 20 is : 3

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