package com.wj; import java.util.LinkedList; import java.util.Queue; public class BST<Key extends Comparable<Key>, Value> { private class Node { private Key key; private Value value; private Node left, right; public Node(Key key, Value value) { this.key = key; this.value = value; this.left = this.right = null; } } private Node root;//根节点 private int count; public BST() { root = null; count = 0; } public void insert(Key key, Value value) { root = insert(root, key, value); } public boolean containsKey(Key key) { return containsKey(root, key); } public Value get(Key key){ Node node = get(root, key); if (node != null) { return node.value; } return null; } private Node get(BST<Key, Value>.Node node, Key key) { if (null == node) return null; if (key.compareTo(node.key) == 0) { return node; } else if (key.compareTo(node.key) < 0) { return get(node.left, key); } else { return get(node.right, key); } } // 二分搜索树的前序遍历 public void preOrder(){ preOrder(root); } // 二分搜索树的中序遍历 public void inOrder(){ inOrder(root); } // 二分搜索树的后序遍历 public void postOrder(){ postOrder(root); } //层序遍历 public void leaveOrder() { Queue<Node> queue = new LinkedList<>(); queue.add(root); while (!queue.isEmpty()) { Node node = queue.poll(); System.out.print(node.key + " "); if (null != node.left) { queue.add(node.left); } if (null != node.right) { queue.add(node.right); } } } //查找最小节点key public Key findMin(){ if (null == root) return null; return findMin(root).key; } //查找最大节点key public Key findMax(){ if (null == root) return null; return findMax(root).key; } //删除最小值 public void deleteMin() { root = deleteMin(root); } //删除最大值 public void deleteMax() { root = deleteMax(root); } //删除任意值 public void remove(Key key){ root = remove(root, key); } public void remove2(Key key){ root = remove2(root, key); } private BST<Key, Value>.Node remove(BST<Key, Value>.Node node, Key key) { if (null == node) return null; if (key.compareTo(node.key) < 0) { node.left = remove(node.left, key); return node; } else if (key.compareTo(node.key) > 0) { node.right = remove(node.right, key); return node; } else { if (node.left == null) { Node nodeRight = node.right; node.right = null; --count; return nodeRight; } else if (node.right == null) { Node nodeLeft = node.left; node.left = null; --count; return nodeLeft; } else { Node nodeRightMin = findMin(node.right); nodeRightMin.right = deleteMin(node.right); nodeRightMin.left = node.left; return nodeRightMin; } } } private BST<Key, Value>.Node remove2(BST<Key, Value>.Node node, Key key) { if (null == node || !containsKey(key)) return node; //获取key位置 Node currentNode = get(node, key); if (currentNode.left == null) { currentNode = currentNode.right; currentNode.right = null; --count; } else if (currentNode.right == null) { currentNode = currentNode.left; currentNode.left = null; --count; } else { Node nodeRightMin = findMin(currentNode.right); nodeRightMin.right = deleteMin(currentNode.right); nodeRightMin.left = currentNode.left; currentNode = nodeRightMin; } return node; } private Node deleteMax(BST<Key, Value>.Node node) { if (node.right == null) { Node leftNode = node.left; node.left = null; --count; return leftNode; } node.right = deleteMax(node.right); return node; } private Node deleteMin(BST<Key, Value>.Node node) { if (node.left == null) { Node nodeRight = node.right; node.right = null; --count; return nodeRight; } node.left = deleteMin(node.left); return node; } private Node findMax(BST<Key, Value>.Node node) { if (node.right == null) return node; return findMax(node.right); } private Node findMin(BST<Key, Value>.Node node) { if (node.left == null) return node; return findMin(node.left); } //清空二分搜索树 // public void clear() { // System.out.println(root); // clear(root); //// root = null; //// count = 0; // } // // private void clear(Node node) { // System.out.println(node); // node = null; // count = 0; // // } private void postOrder(BST<Key, Value>.Node node) { if (null != node) { postOrder(node.left); postOrder(node.right); System.out.print(node.value + " "); } } private void inOrder(BST<Key, Value>.Node node) { if (null != node) { inOrder(node.left); System.out.print(node.value + " "); inOrder(node.right); } } private void preOrder(BST<Key, Value>.Node node) { if (null != node) { System.out.print(node.value + " "); preOrder(node.left); preOrder(node.right); } } private boolean containsKey(BST<Key, Value>.Node node, Key key) { if (null == node) return false; if (key.compareTo(node.key) == 0) { return true; } else if (key.compareTo(node.key) < 0) { return containsKey(node.left, key); } else { return containsKey(node.right, key); } } private Node insert(Node node, Key key, Value value) { if (node == null) { ++count; return new Node(key, value); } else if (key.compareTo(node.key) == 0) { node.value = value; } else if (key.compareTo(node.key) < 0) { node.left = insert(node.left, key, value); } else { node.right = insert(node.right, key, value); } return node; } public static void main(String[] args) throws InterruptedException { // Map<String, String> map = new HashMap<>(); BST<Integer, Integer> bst = new BST<>(); bst.insert(1, 1); bst.insert(2, 2); bst.insert(16, 16); bst.insert(13, 13); bst.insert(49, 49); bst.insert(38, 38); bst.insert(3, 3); bst.insert(3, 3); bst.insert(61, 61); bst.insert(17, 17); // bst.deleteMin(); // bst.deleteMin(); // bst.deleteMin(); // bst.deleteMax(); // bst.deleteMax(); bst.remove2(16); System.out.println(bst.root == null); System.out.println(bst.count); System.out.println(bst.containsKey(3)); System.out.println(bst.get(3)); System.out.println("前驱遍历"); bst.preOrder(); System.out.println(); System.out.println("中驱遍历"); bst.inOrder(); System.out.println(); System.out.println("后驱遍历"); bst.postOrder(); System.out.println(); System.out.println("层序遍历"); bst.leaveOrder(); System.out.println(); System.out.println("最小值" + bst.findMin()); System.out.println("最大值" + bst.findMax()); } }
