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Kth smallest node in BST
MEDIUM
15 mins
19 upvotes
Binary Search Trees
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Kth smallest node in BST

Medium
yellow-spark
0/80
Avg time to solve 15 mins
Success Rate 80 %
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19 upvotes

Problem Statement

You have been given a Binary Search Tree of integers. You are supposed to return the k-th (1-indexed) smallest element in the tree.

For example:
For the given binary search tree and k = 3

Example

The 3rd smallest node is highlighted in yellow colour.   
Detailed explanation ( Input/output format, Notes, Constraints, Images )
Sample Input 1:
3
3
10 5 15 4 7 14 16 -1 -1 -1 -1 -1 -1 -1 -1
1
2 1 3 -1 -1 -1 -1
2
4 -3 5 -1 -1 -1 -1
Sample Output 1:
7
1
4
Explanation of Sample Input 1:
 For the first test case,

Example

The third-smallest node is 7.

For the second test case, the smallest node is 1.

For the third test case, the second-smallest node is 4.
Sample Input 2:
2
2
-2 -4 1 -5 -1 -1 -1 -1 -1
3
10 8 11 -1 -1 -1 -1 -1 -1 -1 -1
Sample Output 2:
-4
11
Explanation of Sample Input 2:
For the first test case, the second-smallest node is -4.

For the second test case, the third-smallest node is 11.
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