Program to check whether one tree is subtree of other or not in Python

Suppose we have two binary trees. We have to check whether second tree is a subtree of first one or not.

So, if the input is like

then the output will be True.

To solve this, we will follow these steps −

• Define a function solve() . This will take root, target

• if root is null and target is also null, then

  • return True

• if root is null or target is null, then

  • return False

• if value of root is same as value of target, then

  • return solve(left of root, left of target) and solve(right of root, right of target)

• otherwise,

  • return solve(left of root, target) or solve(right of root, target)

Let us see the following implementation to get better understanding −

Example

 Live Demo

class TreeNode:
   def __init__(self, data, left = None, right = None):
      self.val = data
      self.left = left
      self.right = right
class Solution:
   def solve(self, root, target):
      if root == None and target == None:
         return True
      if root == None or target == None:
         return False
      if root.val == target.val:
         return self.solve(root.left, target.left) and
self.solve(root.right, target.right)
      else:
         return self.solve(root.left, target) or
self.solve(root.right, target)
ob = Solution()
root1 = TreeNode(6)
root1.left = TreeNode(4)
root1.right = TreeNode(10)
root1.left.left = TreeNode(3)
root1.left.right = TreeNode(5)
root2 = TreeNode(4)
root2.left = TreeNode(3)
root2.right = TreeNode(5)
print(ob.solve(root1, root2))

Input

root1 = TreeNode(6)
root1.left = TreeNode(4)
root1.right = TreeNode(10)
root1.left.left = TreeNode(3)
root1.left.right = TreeNode(5)
root2 = TreeNode(4)
root2.left = TreeNode(3)
root2.right = TreeNode(5)

Output

True

Arnab Chakraborty

Updated on: 21-Oct-2020

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