Program to check whether one value is present in BST or not in Python

Suppose we have a binary search tree and another input called val, we have to check whether val is present in the tree or not.

So, if the input is like

val = 7, then the output will be True, as 7 is present in the tree.

To solve this, we will follow these steps−

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

• if root is null, then

  • return False

• if data of root is same as val, then

  • return True

• if data of root < val, then

  • return solve(left of root, val)

• return solve(right of root, val)

Let us see the following implementation to get better understanding−

Example

class TreeNode:
   def __init__(self, data, left = None, right = None):
      self.data = data
      self.left = left
      self.right = right
class Solution:
   def solve(self, root, val):
      if not root:
         return False
      if root.data == val:
         return True
      if root.data > val:
         return self.solve(root.left, val)
      return self.solve(root.right, val)
ob = Solution()
root = TreeNode(5)
root.left = TreeNode(1)
root.right = TreeNode(9) root.right.left = TreeNode(7) root.right.right = TreeNode(10) root.right.left.left = TreeNode(6) root.right.left.right = TreeNode(8) print(ob.solve(root, 7))

Input

root = TreeNode(5)
root.left = TreeNode(1)
root.right = TreeNode(9)
root.right.left = TreeNode(7)
root.right.right = TreeNode(10)
root.right.left.left = TreeNode(6)
root.right.left.right = TreeNode(8)
7

Output

True