Java实现二叉搜索树及相关操作

package com.tree;

import com.tree.BitNode;

/**
 *
 * 二叉搜索树：一个节点的左子节点的关键字小于这个节点。右子节点的关键字大于或等于这个父节点
 *
 * 注意：不适合插入同样关键字的节点
与平衡二叉树比較：不适合插入有序序列
 */
public class SearchBinTree {

    public static void main(String[] args) {

        BitNode root = new BitNode();
        root.data = 6;
        int[] arr = { 1, 3, 9, 7, 0, 4 };
        for (int i = 0; i < arr.length; i++) {
            insert(root, arr[i]);
        }
        BinTree.levelTraverse(root);
        BitNode successor = getSuccessor(root);
        System.out.println("successor:" + successor.data);


        System.out.println("delete : " + delete(root, 1));
        BinTree.levelTraverse(root);

        // BinTree.levelTraverse(root);
        //
        // BitNode min = getMinNode(root);
        // System.out.println("min = " + min.data);
        //
        // BitNode max = getMaxNode(root);
        // System.out.println("max = " + max.data);

    }

    // 构造二叉搜索树
    public static void insert(BitNode root, int data) {
        BitNode node = new BitNode();
        node.data = data;
        if (root == null) {
            root = node;
        } else {
            if (data < root.data) {
                if (root.lchild == null) {
                    root.lchild = node;
                } else {
                    insert(root.lchild, data);
                }
            } else {
                if (root.rchild == null) {
                    root.rchild = node;
                } else {
                    insert(root.rchild, data);
                }
            }

        }
    }

    // 查找最小节点
    public static BitNode getMinNode(BitNode root) {
        BitNode current, min = null;
        current = root;
        while (current != null) {
            min = current;
            current = current.lchild;
        }
        return min;
    }

    // 查找最大节点
    public static BitNode getMaxNode(BitNode root) {
        BitNode current, max = null;
        current = root;
        while (current != null) {
            max = current;
            current = current.rchild;
        }
        return max;
    }

    // 查找
    public static BitNode find(BitNode root, int data) {
        BitNode current = root;
        while (current.data != data) {
            if (data < current.data)
                current = current.lchild;
            else
                current = current.rchild;
            if (current == null)
                return null;
        }
        return current;
    }

    // 得到简要被删除的节点的后继(中序遍历)
    public static BitNode getSuccessor(BitNode delNode) {
        BitNode successorParent = delNode;
        BitNode successor = delNode;
        BitNode current = delNode.rchild;
        while (current != null) {
            successorParent = successor;
            successor = current;
            current = current.lchild;
        }

        if (successor != delNode.rchild) {
            successorParent.lchild = successor.rchild;
            successor.rchild = delNode.rchild;
        }
        return successor;
    }

    // 删除一个节点----?删除根节点时会出现错误
    public static boolean delete(BitNode root, int data) {
        BitNode current = root;
        BitNode parent = root;
        boolean isLeftChild = true;

        while (current.data != data) {// search for node
            parent = current;
            if (data < current.data) { // go left?

                isLeftChild = true;
                current = current.lchild;
            } else { // go right?

                isLeftChild = false;
                current = current.rchild;
            }

            if (current == null) { // end of th
                return false; // didn't find it
            }
        }

        // found node to delete

        // if no children, simply delete it
        if (current.lchild == null && current.rchild == null) {
            if (current == root) {// if root
                root = null; // tree is empty
            } else if (isLeftChild) {
                parent.lchild = null;// disconnect
            } else { // from parent
                parent.rchild = null;
            }
        } else if (current.rchild == null) {// if no right child replace with
                                            // left subtree
            if (current == root) {
                root = current.lchild;
            } else if (isLeftChild) {
                parent.rchild = current.lchild;
            } else {
                parent.rchild = current.lchild;
            }
        } else if (current.lchild == null) {// if no left child replace with
                                            // right subtree
            if (current == root) {
                root = current.rchild;
            } else if (isLeftChild) {
                parent.lchild = current.rchild;
            } else {
                parent.rchild = current.rchild;
            }
        } else {// two chiledren ,so replace with inorde successor
            //get successor of node to delete(current)
            BitNode successor = getSuccessor(current);
            //connect parent of current to successor instead
            if(current == root){
                root = successor;
            } else if(isLeftChild){
                parent.lchild = successor;
            } else {
                parent.rchild = successor;
            }

            //connect successor to current's left child
            successor.lchild = current.lchild;
        }

        return true;
    }

}