Diameter of binary tree

Author: TonyStark-19

Tree/diameterOfBinaryTree.cpp

@@ -0,0 +1,90 @@
+#include <iostream>
+#include <vector>
+using namespace std;
+
+// Node class
+class Node
+{
+public:
+    int data;
+    Node *left;
+    Node *right;
+
+    Node(int val)
+    {
+        data = val;
+        left = right = NULL;
+    }
+};
+
+static int idx = -1;
+Node *buildTree(vector<int> preorder)
+{
+    idx++;
+
+    // base case
+    if (preorder[idx] == -1)
+    {
+        return NULL;
+    }
+
+    // create root node
+    Node *root = new Node(preorder[idx]);
+
+    // left sub tree recursion call
+    root->left = buildTree(preorder);
+
+    // right sub tree recursion call
+    root->right = buildTree(preorder);
+
+    return root;
+}
+
+// height of tree
+int height(Node *root)
+{
+    // base case
+    if (root == NULL)
+    {
+        return 0;
+    }
+
+    // left subtree call
+    int leftHt = height(root->left);
+
+    // right subtree call
+    int rightHt = height(root->right);
+
+    return max(leftHt, rightHt) + 1;
+}
+
+// diameter of tree
+int diameterOfBinaryTree(Node *root)
+{
+    // base case
+    if (root == NULL)
+    {
+        return 0;
+    }
+
+    // left diameter call
+    int leftDiam = diameterOfBinaryTree(root->left);
+
+    // right diameter call
+    int RightDiam = diameterOfBinaryTree(root->right);
+
+    // current diameter call
+    int currDiam = height(root->left) + height(root->right);
+
+    return max(currDiam, max(leftDiam, RightDiam));
+}
+
+int main()
+{
+    vector<int> preorder = {1, 2, 4, -1, -1, 5, -1, -1, 3, -1, -1};
+    Node *root = buildTree(preorder);
+
+    cout << "Diameter : " << diameterOfBinaryTree(root) << endl;
+
+    return 0;
+}