二进制搜索树代码没有参数

Question

我有以下代码。但它应该没有参数，例如sum((，我不太确定如何修复它，使代码仍然可以工作。有人能帮我吗？我希望尽可能少地更改代码。有没有办法将其添加到方法中，并从中召回回避方法

import java.util.*;
public class BinarySearchTree {
private class BinaryNode {
private int element;
private BinaryNode left;
private BinaryNode right;
private BinaryNode(int element) {
this.element = element;
}
}
private BinaryNode root;
public void insert(int newNumber) {
// special case: empty tree
if (root == null) {
root = new BinaryNode(newNumber);
return;
}
BinaryNode parent = null;
BinaryNode child = root;
while (child != null) {
parent = child;
if (newNumber == child.element) {
//number already in tree
return;
} else if (newNumber < child.element) {
child = child.left;
} else {
child = child.right;
}
}
if (newNumber < parent.element) {
parent.left = new BinaryNode(newNumber);
} else {
parent.right = new BinaryNode(newNumber);
}
}
public int maximumRecursive(BinaryNode root) {
if (root.right == null)
return root.element;
return maximumRecursive(root.right);
}
public int maximumIterative() {
if (root == null) {
throw new NoSuchElementException();
}
BinaryNode current = root;
while (current.right != null)
current = current.right;
return (current.element);
}
public int height(BinaryNode root) {
if (root == null)
return 0;
return 1 + Math.max(height(root.left), height(root.right));
}
public int sum(BinaryNode root) {
if (root == null)
return 0;
return root.element + sum(root.left) + sum(root.right);
}
public String reverseOrder(BinaryNode root) {
if (root == null) {
return "";
}
return reverseOrder(root.right) + " " + ((Integer) root.element).toString() + " " + reverseOrder(root.left);
}

Answer 1

您可以重载sum方法，因此您的版本带有参数，而没有。将带有参数的设置为私有版本，因为该版本只能在递归深化(类内部(期间使用：

private int sum(BinaryNode root) {
if (root == null)
return 0;
return root.element + sum(root.left) + sum(root.right);
}
public int sum() {
return sum(root);
}

您可以对其他递归方法执行类似的操作，因此需要一个参数。例如，对于height:

private int height(BinaryNode root) {
if (root == null)
return 0;
return 1 + Math.max(height(root.left), height(root.right));
}
public int height() {
return height(root);
}