diff --git a/Diameter.cpp b/Diameter.cpp
new file mode 100644
index 0000000..9c325a6
--- /dev/null
+++ b/Diameter.cpp
@@ -0,0 +1,180 @@
+#include <iostream>
+#include <vector>
+
+using namespace std;
+
+class Node
+{
+public:
+    int data=0;
+    Node *left = nullptr;
+    Node *right = nullptr;
+    Node(int data)
+    {
+        this->data = data;
+    }
+};
+
+ class Pair {
+    public:
+    Node *node=nullptr;
+    int state=0;
+
+    Pair(Node *node, int state) {
+      this->node = node;
+      this->state = state;
+    }
+  };
+
+int idx = 0;
+Node *constructTree(vector<int> &arr)
+{
+
+    if (idx == arr.size() || arr[idx] == -1)
+    {
+        idx++;
+        return nullptr;
+    }
+    Node *node = new Node(arr[idx++]);
+    node->left = constructTree(arr);
+    node->right = constructTree(arr);
+    return node;
+}
+
+//Display function
+void display(Node *node)
+{
+    if (node == nullptr)
+        return;
+    string str = "";
+    str += node->left != nullptr ? to_string(node->left->data) : ".";
+    str += " <- " + to_string(node->data) + " -> ";
+    str += node->right != nullptr ? to_string(node->right->data) : ".";
+    cout << str << endl;
+
+    display(node->left);
+    display(node->right);
+}
+
+
+//Height function
+int height(Node *node)
+{
+    return node == nullptr ? -1 : max(height(node->left), height(node->right)) + 1; // for no of edges: -1, and in terms of no of nodes return 0;
+}
+int dia=0;
+
+
+
+int diameter1(Node *root)
+{
+  // write your code here
+  if(root==NULL){
+     return -1;
+
+  }
+
+  int lh=diameter1(root->left);
+  int rh=diameter1(root->right);
+
+  int ht=max(lh,rh)+1;
+  int diamnode=lh+rh+2;
+  if(diamnode>dia){
+     dia=diamnode;
+  }   
+  return ht;
+}
+class DiMover
+{
+  public:
+  int dia=0;
+};
+int diameter2(Node* node,DiMover* dm){
+
+   // write your code here
+   if(node==NULL){
+     return -1;
+
+   }
+
+   int lh=diameter2(node->left,dm);
+   int rh=diameter2(node->right,dm);
+
+   int ht=max(lh,rh)+1;
+   int diamnode=lh+rh+2;
+   if(diamnode>dm->dia){
+     dm->dia=diamnode;
+   }   
+   return ht;
+}
+
+//third approcah and the bad one becauase it has time complexity = o(n^2) 
+//rest all three apriaches has time complexity = o(n);
+int diameter3(Node* node){
+  if(node==NULL){
+    return 0;
+  }
+  int lh=height(node->left);
+  int rh=height(node->right);
+
+  int ld=diameter3(node->left);
+  int rd=diameter3(node->right);
+
+  int nodediam=lh+rh+2;
+  //diameter will the max of diameter of left ,diameter of right,diameter of root;
+  return max(ld,max(rd,nodediam));
+
+}
+
+//4th approch
+class DiaPair
+{
+  public:
+  int ht=-1;
+  int dia=0;
+};
+DiaPair* diameter4(Node* node){
+  if(node==NULL){
+    DiaPair* dnull=new DiaPair();
+    dnull->ht=-1;
+    dnull->dia=0;
+    return dnull;
+  }
+
+  DiaPair* ldp=diameter4(node->left);
+  DiaPair* rdp =diameter4(node->right);
+  DiaPair* ans=new DiaPair();
+
+  ans->ht=max(ldp->ht,rdp->ht)+1;
+  ans->dia=max(ldp->dia,max(rdp->dia,ldp->ht+rdp->ht+2));
+  return ans;
+
+
+
+}
+int main(){
+    int n;
+    cin>>n;
+    
+    vector<int> arr(n,0);
+    for(int i = 0; i < n; i++) {
+        string tmp;
+        cin>>tmp;
+      if (tmp=="n") {
+        arr[i] = -1;
+      } else {
+        arr[i] = stoi(tmp);
+      }
+    }
+    
+    
+    Node * root = constructTree(arr);
+
+    int diam=0;
+    DiMover* dee=new DiMover();
+    dee->dia=0;
+    // DiaPair* ddd=new DiaPair();
+
+    DiaPair* ddd = diameter4(root);
+    cout<<ddd->dia;
+}