DeleteNodeinBST.py

#https://leetcode.com/problems/delete-node-in-a-bst/submissions/

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
  
    def findMinimum(self , root):
      current = root
      while(current.left):
        current = current.left
      return current
      
    def deleteNode(self, root: TreeNode, key: int) -> TreeNode:
      
      if not root:
        return root
      
      
      elif(key < root.val):
        root.left = self.deleteNode(root.left , key)
        
      elif(key > root.val):
        root.right = self.deleteNode(root.right , key)
        
      else:
        
        #Leaf
        if not root.left and not root.right:
          root = None
        
        #1 child   
        elif not root.left:
          root = root.right
          
        elif not root.right :
          root = root.left
          
        #2 child
        else:
          temp = self.findMinimum(root.right)
          root.val = temp.val
          root.right = self.deleteNode(root.right , temp.val)
          
      return root