Day-39: Determine if a tree is sumTree

Author: mandliya

README.md

@@ -5,8 +5,8 @@
 | Current Status|     Stats     |
 | :------------: | :----------: |
 | Total Problems | 58 |
-| Current Streak | 38 |
-| Longest Streak | 38 ( August 17, 2015 - September 23, 2015 ) |
+| Current Streak | 39 |
+| Longest Streak | 39 ( August 17, 2015 - September 24, 2015 ) |
 
 </center>
 
@@ -84,6 +84,7 @@ Include contains single header implementation of data structures and some algori
 |Predecessor and Successor of a given node in Binary Search Tree | [predecessorSuccessor.cpp](tree_problems/predecessorSuccessor.cpp)|
 |Given values of two nodes in a Binary Search Tree, find the Lowest Common Ancestor (LCA). Assume that both the values exist in the tree.| [lowest-common-ancestor.cpp](tree_problems/lowest-common-ancestor.cpp)|
 |Given a binary tree, print out all of its root-to-leaf paths one per line.| [printAllRootToLeafPath.cpp](tree_problems/printAllRootToLeafPath.cpp)
+|Determine if a tree is sum tree. A SumTree is a Binary Tree where the value of a node is equal to sum of the nodes present in its left subtree and right subtree. An empty tree is SumTree and sum of an empty tree can be considered as 0. A leaf node is also considered as SumTree.| [sumTree.cpp](tree_problems/sumTree.cpp)|
 
 
 ### String Problems

tree_problems/sumTree.cpp

@@ -0,0 +1,84 @@
+/**
+ * Problem: Determine if a tree is sum tree.
+ * A SumTree is a Binary Tree where the value of a node is equal to sum of the nodes present in its left subtree and right subtree.
+ * An empty tree is SumTree and sum of an empty tree can be considered as 0.
+ * A leaf node is also considered as SumTree.
+ *
+ *					26
+ *				/   \
+ *		  10     3
+ *		 /    \     \
+ *	  4      6      3
+ */
+#include <iostream>
+
+struct Node {
+  /* data */
+  int data;
+  Node * left;
+  Node * right;
+  Node( int d )
+    : data{ d }, left{ nullptr }, right{ nullptr } { }
+};
+
+/**
+ * addTree - Adds the contents of the tree
+ * @param  root
+ * @return      total of contents of tree
+ */
+int addTree( Node * root ) {
+  if ( root == nullptr ) {
+    return 0;
+  }
+  return (addTree(root->left) + root->data + addTree(root->right)) ;
+}
+
+bool sumTree( Node * root )
+{
+  if ( root == nullptr ) {
+    return true;
+  }
+  else if ( root->left == nullptr && root->right == nullptr ) {
+    return true;
+  }
+  else {
+    if ((addTree(root->left) + addTree(root->right) == root->data) &&
+        sumTree(root->left) && sumTree(root->right)) {
+        return true;
+    } else {
+      return false;
+    }
+  }
+}
+
+void inorder(Node * root)
+{
+    if ( root ) {
+      inorder(root->left);
+      std::cout << root->data << " ";
+      inorder(root->right);
+    }
+}
+
+int main()
+{
+/**
+  *					26
+  *				/   \
+  *		  10     3
+  *		 /    \     \
+  *	  4      6      3
+  */
+  Node * root = new Node(26);
+  root->left = new Node(10);
+  root->right = new Node(3);
+  root->left->left = new Node(4);
+  root->left->right = new Node(6);
+  root->right->right = new Node(3);
+  std::cout << "Inorder of the tree is :";
+  inorder(root);
+  std::cout << std::endl;
+  std::cout << "Is above tree sum-tree? : ";
+  std::cout << ( sumTree(root) ? "Yes\n" : "No\n" );
+  return 0;
+}