Syntax error Program to remove all nodes from BST which are not in range in Python

Program to remove all nodes from BST which are not in range in Python

Suppose we have a BST, an two values low and high, we have to delete all nodes that are not between [low, high] (inclusive).

So, if the input is like

low = 7 high = 10, then the output will be

To solve this, we will follow these steps −

  • Define a function solve() . This will take root, low, high
  • if root is null, then
    • return
  • if low > data of root, then
    • return solve(right of root, low, high)
  • if high < data of root, then
    • return solve(left of root, low, high)
  • right of root := solve(right of root, low, high)
  • left of root := solve(left of root, low, high)
  • return root

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
def print_tree(root):
   if root is not None: print_tree(root.left)
      print(root.data, end = ', ') print_tree(root.right)
class Solution:
   def solve(self, root, low, high):
      if not root:
         return
      if low > root.data:
         return self.solve(root.right,low,high)
      if high < root.data:
         return self.solve(root.left,low,high)
         root.right = self.solve(root.right,low,high)
         root.left = self.solve(root.left,low,high)
      return root
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) low = 7
high = 10
ret = ob.solve(root, low, high) print_tree(ret)

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)
low = 7
high = 10

Output

7, 8, 9, 10,
Updated on: 2020-10-06T05:56:14+05:30

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