dhruv4

#include <bits/stdc++.h>
using namespace std;

/* A binary tree node has data, pointer to left child
   and a pointer to right child */
struct Node {
    int data;
    struct Node* left;
    struct Node* right;
};
Node* newNode(int val) {
    Node* temp = new Node;
    temp->data = val;
    temp->left = NULL;
    temp->right = NULL;
    return temp;
}
Node* buildTree(string str) {
  
    if (str.length() == 0 || str[0] == 'N') return NULL;


    vector<string> ip;

    istringstream iss(str);
    for (string str; iss >> str;) ip.push_back(str);


    Node* root = newNode(stoi(ip[0]));


    queue<Node*> queue;
    queue.push(root);


    int i = 1;
    while (!queue.empty() && i < ip.size()) {

     
        Node* currNode = queue.front();
        queue.pop();

     
        string currVal = ip[i];

        // If the left child is not null
        if (currVal != "N") {

          
            currNode->left = newNode(stoi(currVal));

    
            queue.push(currNode->left);
        }


        i++;
        if (i >= ip.size()) break;
        currVal = ip[i];

     
        if (currVal != "N") {

         
            currNode->right = newNode(stoi(currVal));

            // Push it to the queue
            queue.push(currNode->right);
        }
        i++;
    }

    return root;
}

/* Tree node structure  used in the program

struct Node
{
    int data;
    struct Node* left;
    struct Node* right;

    Node(int x){
        data = x;
        left = right = NULL;
    }
}; */

class Solution {
  private:
    int height(struct Node* node){
        //base case
        if(node == NULL) {
            return 0;
        }
        
        int left = height(node ->left);
        int right = height(node->right);
        
        int ans = max(left, right) + 1;
        return ans;
    }
  public:
  
    
    pair<int,int> diameterFast(Node* root) {
        //base case
        if(root == NULL) {
            pair<int,int> p = make_pair(0,0);
            return p;
        }
        
        pair<int,int> left = diameterFast(root->left);
        pair<int,int> right = diameterFast(root->right);
        
        int op1 = left.first;
        int op2 = right.first;
        int op3 = left.second + right.second + 1;
        
        pair<int,int> ans;
        ans.first = max(op1, max(op2, op3));;
        ans.second = max(left.second , right.second) + 1;

        return ans;
    }
    int diameter(Node* root) {
    
        return diameterFast(root).first;
        
    }
};