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Delete Node In BST
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10 mins
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Binary Search Trees
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Delete Node In BST

Contributed by
Prashansa
Medium
yellow-spark
0/80
Avg time to solve 10 mins
Success Rate 90 %
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16 upvotes

Problem Statement

You have been given a Binary Search Tree of integers with ‘N’ nodes. You are also given data of a node of this tree. Your task is to delete the given node from the BST.

A binary search tree (BST) is a binary tree data structure which has the following properties.

• The left subtree of a node contains only nodes with data less than the node’s data.
• The right subtree of a node contains only nodes with data greater than the node’s data.
• Both the left and right subtrees must also be binary search trees.
Example:
For the given BST, if we want to delete the node with data 5 :

Input

The modified BST will be:

Ouput

Please notice that another valid answer is:

Output

Note :

1. The node which we want to delete will always be present in the given tree.

2. If after deletion the tree becomes empty, print -1.
Detailed explanation ( Input/output format, Notes, Constraints, Images )
Sample Input 1:
1
20 -1 -1
20
15 10 20 8 12 16 25 -1 -1 -1 -1 -1 -1 -1 -1
10
Sample output 1:
-1
8 12 15 16 20 25 
Explanation of Sample output 1:
In test case 1, there is only one node with the value 20, thus after deleting it the tree would be empty.

In test case 2, the tree can be represented as follows:

Example

After the deletion of the node with data 10 the BST will be:

Output

The inorder traversal of this modified BST is 8 12 15 16 20 25.

Another valid modified BST can be:

Output

The inorder traversal of this modified BST is also 8 12 15 16 20 25.
Sample Input 2:
2 
10 5 -1 -1 -1
5
6 4 -1 -1 5
6
Sample output 2:
10
4 5
Explanation of Sample Output 2:
In test case 1, there are only two nodes in the Binary Search Tree and we are deleting the node with value 5. Thus the only node left will the node with value 10.

In test case 2, the tree can be represented as follows:

Example

After the deletion of the node with data 6 the BST will be:

Output

The inorder traversal of this modified BST is 4 5.
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