From 5cc1afaa5e228ec7098f29e353859c319b97df63 Mon Sep 17 00:00:00 2001
From: Udhay <72250606+Udhay-Brahmi@users.noreply.github.com>
Date: Thu, 17 Dec 2020 08:27:37 +0530
Subject: [PATCH] Create Kth largest element in BST

---
 Kth largest element in BST | 134 +++++++++++++++++++++++++++++++++++++
 1 file changed, 134 insertions(+)
 create mode 100644 Kth largest element in BST

diff --git a/Kth largest element in BST b/Kth largest element in BST
new file mode 100644
index 0000000..2766bf5
--- /dev/null
+++ b/Kth largest element in BST	
@@ -0,0 +1,134 @@
+// { Driver Code Starts
+#include <bits/stdc++.h>
+using namespace std;
+
+// Tree Node
+struct Node {
+    int data;
+    Node *left;
+    Node *right;
+
+    Node(int val) {
+        data = val;
+        left = right = NULL;
+    }
+};
+
+// Function to Build Tree
+Node* buildTree(string str)
+{   
+    // Corner Case
+    if(str.length() == 0 || str[0] == 'N')
+            return NULL;
+    
+    // Creating vector of strings from input 
+    // string after spliting by space
+    vector<string> ip;
+    
+    istringstream iss(str);
+    for(string str; iss >> str; )
+        ip.push_back(str);
+        
+    // Create the root of the tree
+    Node* root = new Node(stoi(ip[0]));
+        
+    // Push the root to the queue
+    queue<Node*> queue;
+    queue.push(root);
+        
+    // Starting from the second element
+    int i = 1;
+    while(!queue.empty() && i < ip.size()) {
+            
+        // Get and remove the front of the queue
+        Node* currNode = queue.front();
+        queue.pop();
+            
+        // Get the current node's value from the string
+        string currVal = ip[i];
+            
+        // If the left child is not null
+        if(currVal != "N") {
+                
+            // Create the left child for the current node
+            currNode->left = new Node(stoi(currVal));
+                
+            // Push it to the queue
+            queue.push(currNode->left);
+        }
+            
+        // For the right child
+        i++;
+        if(i >= ip.size())
+            break;
+        currVal = ip[i];
+            
+        // If the right child is not null
+        if(currVal != "N") {
+                
+            // Create the right child for the current node
+            currNode->right = new Node(stoi(currVal));
+                
+            // Push it to the queue
+            queue.push(currNode->right);
+        }
+        i++;
+    }
+    
+    return root;
+}
+
+int kthLargest(Node *root, int k);
+
+int main()
+{
+    int t;
+    cin>>t;
+    getchar();
+    
+    while(t--)
+    {
+        string s;
+        getline(cin,s);
+        Node* head = buildTree(s);
+        
+        int k;
+        cin>>k;
+        getchar();
+        
+        cout << kthLargest( head, k ) << endl;
+    }
+    return 1;
+}// } Driver Code Ends
+
+
+/*The Node structure is defined as
+struct Node {
+    int data;
+    Node *left;
+    Node *right;
+
+    Node(int val) {
+        data = val;
+        left = right = NULL;
+    }
+};
+*/
+
+// return the Kth largest element in the given BST rooted at 'root'
+vector<int> vec;
+void fun(Node *root){
+    if(!root){return;}
+    fun(root->right);
+    vec.push_back(root->data);
+    fun(root->left);
+}
+int kthLargest(Node *root, int k)
+{
+    //Your code here
+    fun(root);
+    sort(vec.begin(),vec.end());
+    int y = vec[vec.size()-k];
+    vec.clear();
+    return y;
+}