Implement Binary Search Tree with basic operations

Author: ArsiyaTasleem90250

BinarySearchTree.java

@@ -0,0 +1,147 @@
+import java.util.Scanner;
+
+public class BinarySearchTree {
+
+    static class Node {
+        int key;
+        Node left, right;
+        Node(int k) {
+            key = k;
+        }
+    }
+
+    Node root;
+
+    public void insert(int key) {
+        root = insertRec(root, key);
+    }
+
+    private Node insertRec(Node node, int key) {
+        if (node == null) {
+            return new Node(key);
+        } else {
+            if (key < node.key) {
+                node.left = insertRec(node.left, key);
+            } else {
+                node.right = insertRec(node.right, key);
+            }
+            return node;
+        }
+    }
+
+    public void delete(int key) {
+        root = deleteRec(root, key);
+    }
+
+    private Node deleteRec(Node node, int key) {
+        if (node == null) {
+            return node;
+        } else {
+            if (key < node.key) {
+                node.left = deleteRec(node.left, key);
+            } else if (key > node.key) {
+                node.right = deleteRec(node.right, key);
+            } else {
+                if (node.left == null) {
+                    return node.right;
+                } else {
+                    if (node.right == null) {
+                        return node.left;
+                    } else {
+                        node.key = minValue(node.right);
+                        node.right = deleteRec(node.right, node.key);
+                    }
+                }
+            }
+            return node;
+        }
+    }
+
+    private int minValue(Node node) {
+        int min = node.key;
+        while (node.left != null) {
+            min = node.left.key;
+            node = node.left;
+        }
+        return min;
+    }
+
+    public void inorder() {
+        inorderRec(root);
+        System.out.println();
+    }
+
+    private void inorderRec(Node node) {
+        if (node != null) {
+            inorderRec(node.left);
+            System.out.print(node.key + " ");
+            inorderRec(node.right);
+        }
+    }
+
+    public void preorder() {
+        preorderRec(root);
+        System.out.println();
+    }
+
+    private void preorderRec(Node node) {
+        if (node != null) {
+            System.out.print(node.key + " ");
+            preorderRec(node.left);
+            preorderRec(node.right);
+        }
+    }
+
+    public void postorder() {
+        postorderRec(root);
+        System.out.println();
+    }
+
+    private void postorderRec(Node node) {
+        if (node != null) {
+            postorderRec(node.left);
+            postorderRec(node.right);
+            System.out.print(node.key + " ");
+        }
+    }
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        BinarySearchTree bst = new BinarySearchTree();
+
+        while (true) {
+            System.out.println("1.Insert  2.Delete  3.Inorder  4.Preorder  5.Postorder  6.Exit");
+            int ch = sc.nextInt();
+
+            if (ch == 1) {
+                System.out.print("Enter value: ");
+                int v = sc.nextInt();
+                bst.insert(v);
+            } else {
+                if (ch == 2) {
+                    System.out.print("Enter value to delete: ");
+                    int v = sc.nextInt();
+                    bst.delete(v);
+                } else {
+                    if (ch == 3) {
+                        bst.inorder();
+                    } else {
+                        if (ch == 4) {
+                            bst.preorder();
+                        } else {
+                            if (ch == 5) {
+                                bst.postorder();
+                            } else {
+                                if (ch == 6) {
+                                    break;
+                                } else {
+                                    System.out.println("Invalid choice");
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+}