Add binary search tree for C++ (#186)

trees/README.md

@@ -5,7 +5,9 @@
 1. [Pre, In & Post Order Traversals](c-or-cpp/pre-in-post-traversal.cpp)
 2. [Level Order Traversal](c-or-cpp/level-order-traversal.cpp)
 3. [Build Binary Tree using Pre,In & Post Order](c-or-cpp/build-binary-tree.cpp)
+4. [Count and find the Sum of nodes in a Binary Tree](c-or-cpp/count-and-sum-of-nodes-in-binary-tree.cpp)
 
 ### Java
 
 1. [Pre, In & Post Order Traversals](java/pre_in_post_traversal.java)
+ 

trees/c-or-cpp/count-and-sum-of-nodes-in-binary-tree.cpp

@@ -0,0 +1,110 @@
+/*
+Problem:
+Count the Number of Nodes in the binary tree, 
+and to find the sum of all nodes in a binary tree.
+*/
+
+/*-------------------------
+Recursive Solution
+Time Complexity: O(n)
+---------------------*/
+
+#include <iostream>
+using namespace std;
+
+// Basic Structure of a tree
+class Node
+{
+private:
+    int data;
+    Node *left;
+    Node *right;
+
+public:
+    Node(int value)
+    {
+        data = value;
+        left = NULL;
+        right = NULL;
+    }
+
+    void insert(Node *&root, int data)
+    {
+
+        if (root == NULL)
+            root = new Node(data);
+        else if (root->data > data)
+            insert(root->left, data);
+        else
+            insert(root->right, data);
+    }
+
+    /* Counting Nodes Algorithm
+
+    Left subtree Count + Right Subtree Count + 1
+
+    */
+
+    int CountNodes(Node *&root)
+    {
+        //Base Case
+        if (root == NULL)
+            return 0;
+ return CountNodes(root->left) + CountNodes(root->right) + 1;
+    }
+
+    /* Sum of Nodes Nodes 
+    Left subtree Sum + Right Subtree Sum + Node Value
+    */
+
+    int SumNodes(Node *&root)
+    {
+        //Base Case
+        if (root == NULL)
+            return 0;
+ return SumNodes(root->left) + SumNodes(root->right) + root->data;
+    }
+};
+
+int main()
+{
+    //User Input
+    Node *root = NULL;
+    int n, num;
+    cout << "Enter the Number of nodes";
+    cin >> n;
+    cout << "Enter the value of the nodes";
+    for (int i = 0; i < n; i++)
+    {
+        cin >> num;
+        root->insert(root, num);
+    }
+
+    //Counting nodes
+    cout << "Number of Nodes : " << root->CountNodes(root) << endl;
+
+    //Sum of Nodes
+    cout << "Sum of Nodes : " << root->SumNodes(root);    
+}
+
+    /*        
+Example:   
+    
+                    1
+                   / \
+                  2   3
+                 / \   \
+                4   5   7    
+        
+    Expected Output:
+    Step 1 - First find the Left subtree Count recursively 
+    Step 2 - Secondly Find  Right Subtree count Recursively
+    Step 3 = Add one for current node
+    You can see here that there are total of 7 nodes in the tree.
+        
+    Similarly as Count node you can find sum of nodes data
+    Step 1 - First find the Left subtree Sum  recursively 
+    Step 2 - Secondly Find  Right Subtree Sum Recursively
+    Step 3 = Add the Current Node Value
+    You can see here that total sum is 28
+*/