java 中的二叉搜索树实现与遍历
Binary search tree implementation in java with traversal
我已经使用插入和遍历方法实现了一个二叉搜索树,但是我没有得到 PreOrder 和 Postorder 的正确输出,我得到的 inOrder 的顺序是正确的。谁能告诉我哪里错了。
我在纸上尝试了相同的示例,但 PreOrder 和 PostOrder 不一样。
这是我的代码
节点Class
package com.BSTTest;
public class Node implements Comparable<Node> {
private int data;
private Node leftChild;
private Node rightChild;
public Node(int data) {
this(data, null, null);
}
public Node(int data, Node leftChild, Node rightChild) {
this.data = data;
this.leftChild = leftChild;
this.rightChild = rightChild;
}
public int getData() {
return data;
}
public void setData(int data) {
this.data = data;
}
public Node getLeftChild() {
return leftChild;
}
public void setLeftChild(Node leftChild) {
this.leftChild = leftChild;
}
public Node getRightChild() {
return rightChild;
}
public void setRightChild(Node rightChild) {
this.rightChild = rightChild;
}
public int compareTo(Node o) {
return Integer.compare(this.data, o.getData());
}
}
树Class
package com.BSTTest;
import com.BSTTest.Node;
public class Tree {
private Node root = null;
public Node getRoot() {
return root;
}
//Inserting data**strong text**
public void insertData(int data) {
Node node = new Node(data, null, null);
if (root == null) {
root = node;
} else {
insert(node, root);
}
}
//Helper method for insert
private void insert(Node node, Node currNode) {
if (node.compareTo(currNode) < 0) {
if (currNode.getLeftChild() == null) {
currNode.setLeftChild(node);
} else {
insert(node, currNode.getLeftChild());
}
} else {
if (currNode.getRightChild() == null) {
currNode.setRightChild(node);
} else {
insert(node, currNode.getRightChild());
}
}
}
public void printInorder() {
printInOrderRec(root);
System.out.println("");
}
//Helper method to recursively print the contents in an inorder way
private void printInOrderRec(Node currRoot) {
if (currRoot == null) {
return;
}
printInOrderRec(currRoot.getLeftChild());
System.out.print(currRoot.getData() + ", ");
printInOrderRec(currRoot.getRightChild());
}
public void printPreorder() {
printPreOrderRec(root);
System.out.println("");
}
// Helper method for PreOrder Traversal recursively
private void printPreOrderRec(Node currRoot) {
if (currRoot == null) {
return;
}
System.out.print(currRoot.getData() + ", ");
printPreOrderRec(currRoot.getLeftChild());
printPreOrderRec(currRoot.getRightChild());
}
public void printPostorder() {
printPostOrderRec(root);
System.out.println("");
}
/**
* Helper method for PostOrder method to recursively print the content
*/
private void printPostOrderRec(Node currRoot) {
if (currRoot == null) {
return;
}
printPostOrderRec(currRoot.getLeftChild());
printPostOrderRec(currRoot.getRightChild());
System.out.print(currRoot.getData() + ", ");
}
//Main Mthod
public static void main(String[] args) {
Tree obj = new Tree();
//Inserting data
obj.insertData(3);
obj.insertData(5);
obj.insertData(6);
obj.insertData(2);
obj.insertData(4);
obj.insertData(1);
obj.insertData(0);
//printing content in Inorder way
System.out.println("Inorder traversal");
obj.printInorder();
//printing content in Inorder way
System.out.println("Preorder Traversal");
obj.printPreorder();
//printing content in Inorder way
System.out.println("Postorder Traversal");
obj.printPostorder();
}
}
看我的朋友,你的代码绝对没问题,因为你提到的输出是绝对正确的。
我认为你没有正确理解二叉搜索树的概念。
你是对的,3是根节点,但是你说1是它的左边是错误的child。
3之后出现的第一个小于3的值是2,所以2剩下child of 3而不是1
如果还有不明白的地方,请参考 Cormenn 的书。
我已经使用插入和遍历方法实现了一个二叉搜索树,但是我没有得到 PreOrder 和 Postorder 的正确输出,我得到的 inOrder 的顺序是正确的。谁能告诉我哪里错了。
我在纸上尝试了相同的示例,但 PreOrder 和 PostOrder 不一样。
这是我的代码
节点Class
package com.BSTTest;
public class Node implements Comparable<Node> {
private int data;
private Node leftChild;
private Node rightChild;
public Node(int data) {
this(data, null, null);
}
public Node(int data, Node leftChild, Node rightChild) {
this.data = data;
this.leftChild = leftChild;
this.rightChild = rightChild;
}
public int getData() {
return data;
}
public void setData(int data) {
this.data = data;
}
public Node getLeftChild() {
return leftChild;
}
public void setLeftChild(Node leftChild) {
this.leftChild = leftChild;
}
public Node getRightChild() {
return rightChild;
}
public void setRightChild(Node rightChild) {
this.rightChild = rightChild;
}
public int compareTo(Node o) {
return Integer.compare(this.data, o.getData());
}
}
树Class
package com.BSTTest;
import com.BSTTest.Node;
public class Tree {
private Node root = null;
public Node getRoot() {
return root;
}
//Inserting data**strong text**
public void insertData(int data) {
Node node = new Node(data, null, null);
if (root == null) {
root = node;
} else {
insert(node, root);
}
}
//Helper method for insert
private void insert(Node node, Node currNode) {
if (node.compareTo(currNode) < 0) {
if (currNode.getLeftChild() == null) {
currNode.setLeftChild(node);
} else {
insert(node, currNode.getLeftChild());
}
} else {
if (currNode.getRightChild() == null) {
currNode.setRightChild(node);
} else {
insert(node, currNode.getRightChild());
}
}
}
public void printInorder() {
printInOrderRec(root);
System.out.println("");
}
//Helper method to recursively print the contents in an inorder way
private void printInOrderRec(Node currRoot) {
if (currRoot == null) {
return;
}
printInOrderRec(currRoot.getLeftChild());
System.out.print(currRoot.getData() + ", ");
printInOrderRec(currRoot.getRightChild());
}
public void printPreorder() {
printPreOrderRec(root);
System.out.println("");
}
// Helper method for PreOrder Traversal recursively
private void printPreOrderRec(Node currRoot) {
if (currRoot == null) {
return;
}
System.out.print(currRoot.getData() + ", ");
printPreOrderRec(currRoot.getLeftChild());
printPreOrderRec(currRoot.getRightChild());
}
public void printPostorder() {
printPostOrderRec(root);
System.out.println("");
}
/**
* Helper method for PostOrder method to recursively print the content
*/
private void printPostOrderRec(Node currRoot) {
if (currRoot == null) {
return;
}
printPostOrderRec(currRoot.getLeftChild());
printPostOrderRec(currRoot.getRightChild());
System.out.print(currRoot.getData() + ", ");
}
//Main Mthod
public static void main(String[] args) {
Tree obj = new Tree();
//Inserting data
obj.insertData(3);
obj.insertData(5);
obj.insertData(6);
obj.insertData(2);
obj.insertData(4);
obj.insertData(1);
obj.insertData(0);
//printing content in Inorder way
System.out.println("Inorder traversal");
obj.printInorder();
//printing content in Inorder way
System.out.println("Preorder Traversal");
obj.printPreorder();
//printing content in Inorder way
System.out.println("Postorder Traversal");
obj.printPostorder();
}
}
看我的朋友,你的代码绝对没问题,因为你提到的输出是绝对正确的。
我认为你没有正确理解二叉搜索树的概念。
你是对的,3是根节点,但是你说1是它的左边是错误的child。
3之后出现的第一个小于3的值是2,所以2剩下child of 3而不是1
如果还有不明白的地方,请参考 Cormenn 的书。