chore(CPlusPlus): add sum of right leaves in binary tree (#689)

algorithms/CPlusPlus/README.md

@@ -139,6 +139,7 @@
 - [Finding the elements of a tree visible from top view](Trees/Top-View-Of-A-Tree.cpp)
 - [Binary Tree Implementation](Trees/binary-tree-implementation.cpp)
 - [Iterative Segment Tree](Trees/IterativeSegmentTree.cpp)
+- [Sum of right leaves](Trees/sum-of-right-leaves.cpp)
 
 ## Trie
 

algorithms/CPlusPlus/Trees/sum-of-right-leaves.cpp

@@ -0,0 +1,81 @@
+// The sum of right leaves algorithm uses a queue to navigate through a binary tree
+// Worst Case Time Complexity: O(n)
+// Average Time Complexity: O(n)
+
+#include <iostream>
+#include <queue>
+
+using namespace std;
+
+// Node structure for tree
+struct Node {
+    int val;
+    Node *left;
+    Node *right;
+
+    Node(int val) {
+        this->val = val;
+        left = nullptr;
+        right = nullptr;
+    }
+};
+
+int sumRightLeaves(Node* root) {
+    queue<Node*> q;
+    int rightSum = 0;
+
+    // Checking if the root is nullptr push to queue if it exists
+    if(root)
+    {
+        q.push(root);
+    }
+
+    while(!q.empty())
+    {
+        // Check if there exists a right node
+        if(q.front()->right)
+        {
+            // Check if this is a leaf node
+            if(q.front()->right->right == nullptr && q.front()->right->left == nullptr)
+            {
+                rightSum += q.front()->right->val;
+            }
+            else
+            {
+                q.push(q.front()->right);
+            }
+        }
+        if(q.front()->left) // Check down left side of tree
+        {
+            q.push(q.front()->left);
+        }
+
+        q.pop();
+    }
+
+    return rightSum;
+}
+
+int main()
+{
+    Node* root = new Node(3);
+    root->left = new Node(5);
+    root->right = new Node(7);
+    root->left->left = new Node(8);
+    root->left->right = new Node(10);
+    root->right->right = new Node(13);
+
+//                     3
+//                    / \
+//                   5   7
+//                  / \   \
+//                 8   10  13
+//
+//          Sample Output
+//          Sum of the right leaves: 23
+
+// Outputting sum of right leaves
+    cout << "Sum of right leaves: " << sumRightLeaves(root);
+
+    return 0;
+}