DiameterofBinaryTree.cpp

#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) {
    // 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 = newNode(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 = newNode(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 = newNode(stoi(currVal));

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

    return root;
}
/* Function to get diameter of a binary tree */
int diameter(struct Node* tree);

/* Driver program to test size function*/
int main() {
    int t;
    scanf("%d\n", &t);
    while (t--) {
        string s;
        getline(cin, s);
        Node* root = buildTree(s);
        cout << diameter(root) << endl;
    }
    return 0;
}
// } Driver Code Ends

/*int height( Node* node){
       if(node==NULL) return 0;
      return 1+max(height(node->left),height(node->right));
   }
   
int diameter(Node* node) {
   int rheight=height(node->right);
   int lheight=height(node->left);
   
   int ldiameter=diameter(node->left);
   int rdiameter=diameter(node->right);
   
   return max(lheight+rheight+1,max(ldiameter,rdiameter));
  
}*/

int height( Node* node){
if(node == NULL)
        return 0;
    return 1 + max(height(node->left), height(node->right));
} 

int diameter( struct Node * node)
{
  
    if (node == NULL)
        return 0;
    
    int lheight = height(node->left);
    int rheight = height(node->right);

    int ldiameter = diameter(node->left);
    int rdiameter = diameter(node->right);
    
    return max(lheight + rheight + 1, max(ldiameter, rdiameter));
}