Java-二叉树-插入、删除、遍历

二叉树的具体特性和细节知识点，自行百度，直接上代码。

节点：节点内容、左子孩子、右子孩子、父亲

class Node {
private int data;
private Node leftChild;
private Node rightChild;
private Node parent;

public Node getParent() {
return parent;
}

public void setParent(Node parent) {
this.parent = parent;
}

public Node(int data, Node leftChild, Node rightChild, Node parent) {
this.data = data;
this.leftChild = leftChild;
this.rightChild = rightChild;
this.parent = parent;

}

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;
}

}

二叉树构造和操作：
public class BinaryTree {
private Node root;//根节点
//插入节点
public void insertNode(Node root, Node node) {

Node current = root;
while (true) {
if (node.getData() < current.getData()) {
if (current.getLeftChild() == null) {
node.setParent(current);
current.setLeftChild(node);
break;
} else {
current = current.getLeftChild();
}
} else {
if (current.getRightChild() == null) {
node.setParent(current);
current.setRightChild(node);
break;
} else {
current = current.getRightChild();
}

}
}
}
//删除节点
public void deleteNode(Node node) {
if (node.equals(root)) {
root = null;
} else if (node.getParent() != null) {
if (node == node.getParent().getLeftChild()) {
node.getParent().setLeftChild(null);
} else {
node.getParent().setRightChild(null);

}
}
}

//获取某节点的高度
public int geHeight(Node node) {
if (node == null) {
return 0;
} else {
int leftHeight = geHeight(node.getLeftChild());
int rightHeight = geHeight(node.getRightChild());
int max = Math.max(leftHeight, rightHeight);
return max + 1;
}
}

//获取某节点的子节点个数
public int getChildNodes(Node node) {
if (node == null) {
return 0;
} else {
int leftNodes = getChildNodes(node.getLeftChild());
int rightNodes = getChildNodes(node.getRightChild());
return leftNodes + rightNodes + 1;
}
}

//先序遍历树
public void PreOrder(Node root) {
if (root == null)
return;
System.out.print(root.getData() + " ");
PreOrder(root.getLeftChild());
PreOrder(root.getRightChild());
}

//中序
public void MidOrder(Node root) {
if (root == null) return;
MidOrder(root.getLeftChild());
System.out.print(root.getData() + " ");
MidOrder(root.getRightChild());
}

//后序
public void LastOrder(Node root) {
if (root == null) return;
LastOrder(root.getLeftChild());
LastOrder(root.getRightChild());
System.out.print(root.getData() + " ");

}

public BinaryTree() {

}

public BinaryTree(Node root) {
this.root = root;
}

public Node getRoot() {
return root;
}

public void setRoot(Node root) {
this.root = root;
}

}


测试：
public class Main {
public static void main(String[] args) {
BinaryTree bt = new BinaryTree(new Node(1, null, null, null));
int a[] = {5, 3, 2, 7, 4, 9, 8};
for (int i = 0; i < 7; i++) {
bt.insertNode(bt.getRoot(), new Node(a[i], null, null, null));
}
// System.out.println(bt.geHeight(root));//高度
// bt.PreOrder(root);
// System.out.println();
// bt.MidOrder(root);
// System.out.println();
// bt.LastOrder(root);
// System.out.println();
// bt.deleteNode(bt.getRoot());
// bt.PreOrder(bt.getRoot());
// System.out.println(bt.getChildNodes(bt.getRoot()));//子节点数

}
}