Java对二叉搜索树进行插入、查找、遍历、最大值和最小值的操作

标签：二叉搜索树

1、首先，需要一个节点对象的类。这些对象包含数据，数据代表存储的内容，而且还有指向节点的两个子节点的引用

class Node {
	public int iData;
	public double dData;
	public Node leftChild;
	public Node rightChild;
	public void displayNode() {
		System.out.print("{");
		System.out.print(iData);
		System.out.print(",");
		System.out.print(dData);
		System.out.print("}");
	}
}

从根开始查找一个相应的节点，它将是新节点的父节点。当父节点找到了，新节点就可以连接到它的左子节点或右子节点处，这取决于新节点的值是比父节点的值大还是小。

下面是insert()方法代码：

public void insert(int id, double dd) {
		Node newNode = new Node();
		newNode.iData = id;
		newNode.dData = dd;
		if(root == null)
			root = newNode;
		else {
			Node current = root;
			Node parent;
			while(true) {
				parent = current;
				if(id < current.iData) {
					current = current.leftChild;
					if(current == null) {
						parent.leftChild = newNode;
						return;
					}
				} else {
					current = current.rightChild;
					if(current == null) {
						parent.rightChild = newNode;
						return;
					}
				}
			} // end while
		} // end else
	}

3、查找一个节点

public Node find(int key) {
		// 假设树非空
		Node current = root;
		while(current.iData != key) {
			if(key < current.iData)
				current = current.leftChild;
			else
				current = current.rightChild;
			if(current == null)
				return null;
		}
		return current;
	}

找不到节点：如果current等于null，在查找序列中找不到下一个子节点，到达序列的末端而没有找到要找的节点，表明了它不存在，返回nulll来指出这个情况。

4、遍历树（前序遍历，中序遍历，后序遍历）

/**
	 * 前序遍历
	 * @param localRoot
	 */
	public void preOrder(Node localRoot) {
		if(localRoot != null) {
			System.out.print(localRoot.iData+" ");
			preOrder(localRoot.leftChild);
			preOrder(localRoot.rightChild);
		}
	}
	
	/**
	 * 中序遍历
	 * @param localRoot
	 */
	public void inOrder(Node localRoot) {
		if(localRoot != null) {
			preOrder(localRoot.leftChild);
			System.out.print(localRoot.iData+" ");
			preOrder(localRoot.rightChild);
		}
	}
	
	/**
	 * 后序遍历
	 * @param localRoot
	 */
	public void postOrder(Node localRoot) {
		if(localRoot != null) {
			preOrder(localRoot.leftChild);
			preOrder(localRoot.rightChild);
			System.out.print(localRoot.iData+" ");
		}
	}

1）、调用自身来遍历节点的左子树

2）、访问这个节点

3）、调用自身来遍历节点的右子树。

5、查找最大值和最小值

/**
	 * 求树中的最小值
	 * @return
	 */
	public Node minimum() {
		Node current;
		current = root;
		Node last = null;
		while(current != null) {
			last = current;
			current = current.leftChild;
		}
		return last;
	}
	
	/**
	 * 求树中的最大值
	 * @return
	 */
	public Node maxmum() {
		Node current;
		current = root;
		Node last = null;
		while(current != null) {
			last = current;
			current = current.rightChild;
		}
		return last;
	}

以下是完整测试代码：

package binTree;

class Node {
	public int iData;
	public double dData;
	public Node leftChild;
	public Node rightChild;
	public void displayNode() {
		System.out.print("{");
		System.out.print(iData);
		System.out.print(",");
		System.out.print(dData);
		System.out.print("}");
	}
}

class Tree {
	private Node root;
	public Tree() {
		root = null;
	}
	/**
	 * 查找节点
	 * @param key
	 * @return
	 */
	public Node find(int key) {
		// 假设树非空
		Node current = root;
		while(current.iData != key) {
			if(key < current.iData)
				current = current.leftChild;
			else
				current = current.rightChild;
			if(current == null)
				return null;
		}
		return current;
	}
	/**
	 * 插入节点
	 * @param id
	 * @param dd
	 */
	public void insert(int id, double dd) {
		Node newNode = new Node();
		newNode.iData = id;
		newNode.dData = dd;
		if(root == null)
			root = newNode;
		else {
			Node current = root;
			Node parent;
			while(true) {
				parent = current;
				if(id < current.iData) {
					current = current.leftChild;
					if(current == null) {
						parent.leftChild = newNode;
						return;
					}
				} else {
					current = current.rightChild;
					if(current == null) {
						parent.rightChild = newNode;
						return;
					}
				}
			} // end while
		} // end else
	}
	/**
	 * 前序遍历
	 * @param localRoot
	 */
	public void preOrder(Node localRoot) {
		if(localRoot != null) {
			System.out.print(localRoot.iData+" ");
			preOrder(localRoot.leftChild);
			preOrder(localRoot.rightChild);
		}
	}
	
	/**
	 * 中序遍历
	 * @param localRoot
	 */
	public void inOrder(Node localRoot) {
		if(localRoot != null) {
			preOrder(localRoot.leftChild);
			System.out.print(localRoot.iData+" ");
			preOrder(localRoot.rightChild);
		}
	}
	
	/**
	 * 后序遍历
	 * @param localRoot
	 */
	public void postOrder(Node localRoot) {
		if(localRoot != null) {
			preOrder(localRoot.leftChild);
			preOrder(localRoot.rightChild);
			System.out.print(localRoot.iData+" ");
		}
	}
	
	/**
	 * 求树中的最小值
	 * @return
	 */
	public Node minimum() {
		Node current;
		current = root;
		Node last = null;
		while(current != null) {
			last = current;
			current = current.leftChild;
		}
		return last;
	}
	
	/**
	 * 求树中的最大值
	 * @return
	 */
	public Node maxmum() {
		Node current;
		current = root;
		Node last = null;
		while(current != null) {
			last = current;
			current = current.rightChild;
		}
		return last;
	}
}

public class TreeApp {
	public static void main(String[] args) {
		Tree theTree = new Tree();
		/**
		 *                50
		 *               /  		 *              25  75
		 *             / \    		 *            12 37   87
		 *               / \    		 *              30 43   93
		 *               \        		 *                33      97
		 */
		theTree.insert(50, 1.5);
		theTree.insert(25, 1.2);
		theTree.insert(75, 1.7);
		theTree.insert(12, 1.5);
		theTree.insert(37, 1.2);
		theTree.insert(43, 1.7);
		theTree.insert(30, 1.5);
		theTree.insert(33, 1.2);
		theTree.insert(87, 1.7);
		theTree.insert(93, 1.5);
		theTree.insert(97, 1.5);
		System.out.println("插入完毕~");
		
		//找到root节点
		Node nodeRoot = theTree.find(50);
		// 中序遍历
		theTree.inOrder(nodeRoot);
		System.out.println();
		// 求最小值
		System.out.println("mini:"+ theTree.minimum().iData);
		// 求最大值
		System.out.println("max:"+ theTree.maxmum().iData);
		
	}
}

Java对二叉搜索树进行插入、查找、遍历、最大值和最小值的操作

标签：二叉搜索树

原文地址：http://blog.csdn.net/victor_cindy1/article/details/46636923