二叉查找数 插入 删除

package search;

public class BinarySearchTree {

	/**
	 * @param args
	 */
	public static void main(String[] args) {

		int a[] = new int[] { 8,7,3,10,2,5,4,6 };
		Node root = buildBinaryTree(a);
		traverse(root);

		// delet node
		System.out.println("\nAfter delete:");
		deleteTree(root, 3);
		traverse(root);
	}

	public static void traverse(Node root) {
		if (root == null) {
			return;
		}
		traverse(root.left);
		System.out.print(root.value + " ");
		traverse(root.right);

	}

	public static Node buildBinaryTree(int a[]) {
		// chose the first to be root. u can still randomly choose the
		// first(root).
		Node root = new Node(a[0], null, null, null);
		for (int i = 1; i < a.length; i++) {
			insertTree(root, a[i]);
		}
		return root;

	}

	// assume value is distinct
	public static int deleteTree(Node root, int value) {
		// -1 -> not find 0 -> OK
		// get the Node
		Node t = root;
		boolean isleft = true;
		boolean find = false;
		while (t != null) {
			if (t.value == value) {
				find = true;
				break;
			} else if (t.value > value) {
				t = t.left;
				isleft = true;
			} else {
				t = t.right;
				isleft = false;
			}
		}

		// find one.
		if (!find) {
			return -1;
		}
		// if node has no child.
		if (t.left == null && t.right == null) {
			if (isleft)
			{
				t.parent.left = null;
			}
			else
			{
				t.parent.right=null;
			}
			t = null;
			return 0;
		}

		if (t.left != null && t.right != null) {
			// must be careful
			// find the right minnum not null node.
			Node r = t.right;
			while (r.left != null) {
				r = r.left;
			}
			// make sure the value
			if (isleft) {
				t.parent.left = r;

			} else {
				t.parent.right = r;
			}
			r.left = t.left;
			r.right = t.right;
			r.parent.left = null;
			r.parent = t.parent;
			
			t = null;
			return 0;
		}
		// only one child.
		if (t.left == null) {
			t.parent.right = t.right;
			t = null;
		} else {
			t.parent.left = t.left;
			t = null;
		}
		return 0;

	}

	// root cann't be null.
	public static void insertTree(Node root, int value) {
		Node cur = root;
		Node lastNode = null;
		boolean useleft = true;
		while (cur != null) {
			lastNode = cur;
			if (cur.value >= value) {
				cur = cur.left;
				useleft = true;
			} else {
				cur = cur.right;
				useleft = false;
			}

		}

		if (useleft) {
			lastNode.left = new Node(value, null, null, lastNode);
		} else {
			lastNode.right = new Node(value, null, null, lastNode);
		}
	}

}

class Node {
	Node left, right, parent;
	int value;

	public Node(int v) {
		value = v;
	}

	public Node(int v, Node left, Node right, Node parent) {
		value = v;
		this.right = right;
		this.left = left;
		this.parent = parent;
	}

	public String toString() {
		return (left == null ? null : left.value) + "," + (value) + ","
				+ (right == null ? null : right.value);
	}

}

删除分3种情况：

【1】左右节点都没空，则直接移除该节点。

【2】有一个子节点，则连接其子节点与其父节点

【3】有2个子节点，则找到该节点右子树中最左边的节点，替换。