Merge pull request #1104 from Ronik-Shah/patch-3

Splay Tree

Tree/Splay

@@ -0,0 +1,154 @@
+// Java implementation for above approach 
+class Splay
+{ 
+
+// An AVL tree node  
+static class node{  
+
+    int key;  
+    node left, right;  
+};  
+
+static node newNode(int key){  
+    node Node = new node(); 
+    Node.key = key;  
+    Node.left = Node.right = null;  
+    return (Node);  
+}  
+
+// A utility function to right  
+// rotate subtree rooted with y  
+// See the diagram given above.  
+static node rightRotate(node x)  
+{  
+    node y = x.left;  
+    x.left = y.right;  
+    y.right = x;  
+    return y;  
+}  
+
+// A utility function to left  
+// rotate subtree rooted with x  
+// See the diagram given above.  
+static node leftRotate(node x)  
+{  
+    node y = x.right;  
+    x.right = y.left;  
+    y.left = x;  
+    return y;  
+}  
+
+// This function brings the key at 
+// root if key is present in tree.  
+// If key is not present, then it 
+// brings the last accessed item at  
+// root. This function modifies the 
+// tree and returns the new root  
+static node splay(node root, int key)  
+{  
+    // Base cases: root is null or 
+    // key is present at root  
+    if (root == null || root.key == key)  
+        return root;  
+
+    // Key lies in left subtree  
+    if (root.key > key)  
+    {  
+        // Key is not in tree, we are done  
+        if (root.left == null) return root;  
+
+        // Zig-Zig (Left Left)  
+        if (root.left.key > key)  
+        {  
+            // First recursively bring the 
+            // key as root of left-left  
+            root.left.left = splay(root.left.left, key);  
+
+            // Do first rotation for root,  
+            // second rotation is done after else  
+            root = rightRotate(root);  
+        }  
+        else if (root.left.key < key) // Zig-Zag (Left Right)  
+        {  
+            // First recursively bring 
+            // the key as root of left-right  
+            root.left.right = splay(root.left.right, key);  
+
+            // Do first rotation for root.left  
+            if (root.left.right != null)  
+                root.left = leftRotate(root.left);  
+        }  
+
+        // Do second rotation for root  
+        return (root.left == null) ?  
+                              root : rightRotate(root);  
+    }  
+    else // Key lies in right subtree  
+    {  
+        // Key is not in tree, we are done  
+        if (root.right == null) return root;  
+
+        // Zag-Zig (Right Left)  
+        if (root.right.key > key)  
+        {  
+            // Bring the key as root of right-left  
+            root.right.left = splay(root.right.left, key);  
+
+            // Do first rotation for root.right  
+            if (root.right.left != null)  
+                root.right = rightRotate(root.right);  
+        }  
+        else if (root.right.key < key)// Zag-Zag (Right Right)  
+        {  
+            // Bring the key as root of  
+            // right-right and do first rotation  
+            root.right.right = splay(root.right.right, key);  
+            root = leftRotate(root);  
+        }  
+
+        // Do second rotation for root  
+        return (root.right == null) ?  
+                               root : leftRotate(root);  
+    }  
+}  
+
+// The search function for Splay tree.  
+// Note that this function returns the  
+// new root of Splay Tree. If key is  
+// present in tree then, it is moved to root.  
+static node search(node root, int key)  
+{  
+    return splay(root, key);  
+}  
+
+// A utility function to print  
+// preorder traversal of the tree.  
+// The function also prints height of every node  
+static void preOrder(node root)  
+{  
+    if (root != null)  
+    {  
+        System.out.print(root.key + " ");  
+        preOrder(root.left);  
+        preOrder(root.right);  
+    }  
+}  
+
+// Driver code 
+public static void main(String[] args)  
+{  
+    node root = newNode(100);  
+    root.left = newNode(50);  
+    root.right = newNode(200);  
+    root.left.left = newNode(40);  
+    root.left.left.left = newNode(30);  
+    root.left.left.left.left = newNode(20);  
+
+    root = search(root, 20);  
+    System.out.print("Preorder traversal of the" +   
+                     " modified Splay tree is \n");  
+    preOrder(root);  
+}  
+}  
+
+// This code is contributed by 29AjayKumar