Merge pull request codemistic#479 from Aman5989/patch-18

create clone-a-Binary-tree-with-random-pointer.cpp

Author: gantavyamalviya

Hashtable/Clone-a-Binary-Tree-with-Random-Pointers.cpp

@@ -0,0 +1,119 @@
+// A hashmap based C++ program to clone a binary
+// tree with random pointers
+#include<iostream>
+#include<unordered_map>
+using namespace std;
+
+/* A binary tree node has data, pointer to left child,
+a pointer to right child and a pointer to
+random node*/
+struct Node
+{
+int key;
+struct Node* left, *right, *random;
+};
+
+/* Helper function that allocates a new Node with the
+given data and NULL left, right and random pointers. */
+Node* newNode(int key)
+{
+Node* temp = new Node;
+temp->key = key;
+temp->random = temp->right = temp->left = NULL;
+return (temp);
+}
+
+/* Given a binary tree, print its Nodes in inorder*/
+void printInorder(Node* node)
+{
+if (node == NULL)
+return;
+
+/* First recur on left subtree */
+printInorder(node->left);
+
+/* then print data of Node and its random */
+cout << "[" << node->key << " ";
+if (node->random == NULL)
+cout << "NULL], ";
+else
+cout << node->random->key << "], ";
+
+/* now recur on right subtree */
+printInorder(node->right);
+}
+
+/* This function creates clone by copying key
+and left and right pointers. This function also
+stores mapping from given tree node to clone. */
+Node* copyLeftRightNode(Node* treeNode, unordered_map<Node *, Node *> &mymap)
+{
+if (treeNode == NULL)
+return NULL;
+Node* cloneNode = newNode(treeNode->key);
+mymap[treeNode] = cloneNode;
+cloneNode->left = copyLeftRightNode(treeNode->left, mymap);
+cloneNode->right = copyLeftRightNode(treeNode->right, mymap);
+return cloneNode;
+}
+
+// This function copies random node by using the hashmap built by
+// copyLeftRightNode()
+void copyRandom(Node* treeNode, Node* cloneNode, unordered_map<Node *, Node *> &mymap)
+{
+if (cloneNode == NULL)
+return;
+cloneNode->random = mymap[treeNode->random];
+copyRandom(treeNode->left, cloneNode->left, mymap);
+copyRandom(treeNode->right, cloneNode->right, mymap);
+}
+
+// This function makes the clone of given tree. It mainly uses
+// copyLeftRightNode() and copyRandom()
+Node* cloneTree(Node* tree)
+{
+if (tree == NULL)
+return NULL;
+unordered_map<Node *, Node *> mymap;
+Node* newTree = copyLeftRightNode(tree, mymap);
+copyRandom(tree, newTree, mymap);
+return newTree;
+}
+
+/* Driver program to test above functions*/
+int main()
+{
+//Test No 1
+Node *tree = newNode(1);
+tree->left = newNode(2);
+tree->right = newNode(3);
+tree->left->left = newNode(4);
+tree->left->right = newNode(5);
+tree->random = tree->left->right;
+tree->left->left->random = tree;
+tree->left->right->random = tree->right;
+
+// Test No 2
+// tree = NULL;
+
+// Test No 3
+// tree = newNode(1);
+
+// Test No 4
+/* tree = newNode(1);
+tree->left = newNode(2);
+tree->right = newNode(3);
+tree->random = tree->right;
+tree->left->random = tree;
+*/
+
+cout << "Inorder traversal of original binary tree is: \n";
+printInorder(tree);
+
+Node *clone = cloneTree(tree);
+
+cout << "\n\nInorder traversal of cloned binary tree is: \n";
+printInorder(clone);
+
+return 0;
+}