Kth Largest in BST
https://workat.tech/problem-solving/practice/kth-largest-element-bst
Given the root node of a binary search tree and a number k, find out the kth largest element (1-indexed) in the BST.
Note: You can assume that k <= number of nodes.
Testing
Input Format
The first line contains an integer T denoting the number of test cases.
For each test case, the input has 2 lines:
- The first line contains an integer n denoting the number of nodes in the tree (including the NULL nodes).
- The second line contains n space-separated integers that will form the binary tree. The integers follow level order traversal of the tree where -1 indicates a NULL node.
- The third line contains an integer k.
Output Format
For each test case, the output contains an integer with the value of the kth largest element in BST.
Sample Input
4
9
2 1 3 -1 -1 -1 5 4 7
4
7
6 3 21 -1 -1 -1 89
1
12
8 3 9 -1 4 -1 10 -1 -1 -1 12 11
7
4
28 14 -1 11
2Expected Output
3
89
3
141 <= T <= 101 <= n <= 1051 <= node value <= 109
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Related problems
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| class Solution { | |
| /* This is the Node class definition | |
| class Node { | |
| public Node left; | |
| public Node right; | |
| public int data; | |
| public Node(int data) { | |
| this.data = data; | |
| } | |
| } | |
| */ | |
| int findKthLargest(Node root, int k) { | |
| Stack<Node> stack = new Stack<Node>(); | |
| stack.push(root); | |
| while (!stack.isEmpty()) { | |
| while (root != null) { | |
| stack.push(root); | |
| root = root.right; | |
| } | |
| root = stack.pop(); | |
| k -=1; | |
| if (k == 0) { | |
| return root.data; | |
| } | |
| root = root.left; | |
| } | |
| return -1; | |
| } | |
| } |
