Showing:
Handle Score
@Ibrahim Nash 6560
@mb1973 5777
@Quandray 5275
@akhayrutdinov 5111
@saiujwal13083 5074
@kirtidee18 4408
@sanjay05 3762
@mantu_singh 3666
@gfgaccount 3605
@marius_valentin_dragoi 3525
Check for BST
Easy Accuracy: 21.58% Submissions: 100k+ Points: 2

Given a binary tree. Check whether it is a BST or not.
Note: We are considering that BSTs can not contain duplicate Nodes.

Example 1:

Input:
2
/    \
1      3
Output: 1
Explanation:
The left subtree of root node contains node
with key lesser than the root node’s key and
the right subtree of root node contains node
with key greater than the root node’s key.
Hence, the tree is a BST.


Example 2:

Input:
2
\
7
\
6
\
5
\
9
\
2
\
6
Output: 0
Explanation:
Since the node with value 7 has right subtree
nodes with keys less than 7, this is not a BST.


isBST() which takes the root of the tree as a parameter and returns true if the given binary tree is BST, else returns false

Expected Time Complexity: O(N).
Expected Auxiliary Space: O(Height of the BST).

Constraints:
0 <= Number of edges <= 100000