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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

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

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

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