diff --git a/TreesAlgorithms/diameterOfBinaryTree/diameter_binary_tree.cpp b/TreesAlgorithms/diameterOfBinaryTree/diameter_binary_tree.cpp
new file mode 100644
index 0000000..5b8e800
--- /dev/null
+++ b/TreesAlgorithms/diameterOfBinaryTree/diameter_binary_tree.cpp
@@ -0,0 +1,26 @@
+
+// https://leetcode.com/problems/diameter-of-binary-tree/
+
+class Solution {
+public:
+    int d=0;
+    int height(TreeNode* curr_node)
+    {
+        if(curr_node ==NULL)
+            return 0;
+        int lh = height(curr_node ->left);
+        int rh = height(curr_node ->right);
+        
+        d = max(d , lh+rh); //calculate diameter across each node as root and update if it is max.
+        
+        return max(lh+1,rh+1); //return max height
+        
+    }
+    int diameterOfBinaryTree(TreeNode* root) 
+    {
+        
+        height(root);
+        return d;
+        
+    }
+};
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