Kth largest element in BST(using extraspace).cpp

//{ 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;
}


// } 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'
class Solution
{
    public:
    void solve(Node* root, vector<int>&data){
        if(root==NULL) return ;
        solve(root->left,data);
        data.push_back(root->data);
        solve(root->right,data);
    }
    int kthLargest(Node *root, int K)
    {
        //Your code here
        vector<int>data;
        solve(root,data);
        // for(auto i : data){
        //     cout<<i<<" ";
        // }
        // cout<<endl;
        
        return data[data.size()-K];
    }
};

//{ Driver Code Starts.

int main()
{
    int t;
    cin>>t;
    getchar();
    
    while(t--)
    {
        string s;
        getline(cin,s);
        Node* head = buildTree(s);
        
        int k;
        cin>>k;
        getchar();
        
        Solution ob;
        cout << ob.kthLargest( head, k ) << endl;
    }
    return 1;
}
// } Driver Code Ends