我一直在这段代码上工作了一段时间,没有运气。我知道我需要通过这种方法来传递我的树,但是我不确定如何做到这一点。
我认为我的算法是正确的,但是无论我输入什么内容,它都会告诉我“ null”。任何反馈都可以提供帮助,我认为它一直返回null,因为我不知道如何将树传递给该方法。
下面,我的find2方法应该使用我的add2方法创建的树来找到选定的节点。这也包括我的主要方法。
这里是代码:
public boolean add2(E item) {
root = add2(root, item);
return addReturn;
}
private Node<E> add2(Node<E> localRoot, E item){
if(localRoot == null) {
//Adding item if tree is empty...
addReturn = true;
return new Node<>(item);
} else if (item.compareTo(localRoot.data) == 0) {
//Returning item if equal to root...
addReturn = false;
return localRoot;
} else if (item.compareTo(localRoot.data) < 0) {
//Adding item to right side of tree if less than the root...
localRoot.right = add(localRoot.right, item);
return localRoot;
} else {
//Adding item to left side of tree if grater than the root...
localRoot.left = add(localRoot.left, item);
return localRoot;
}
}
//wrapper method
public E find2(E target) {
return find2(root, target);
}
//recursive method
private E find2(Node<E> localRoot, E target) {
if(localRoot == null) {
return null;
}
int compResult2 = target.compareTo(localRoot.data);
if(compResult2 == 0) {
return localRoot.data;
} else if (compResult2 < 0) {
return find2(localRoot.right, target);
} else {
return find2(localRoot.left, target);
}
}
public class BinarySearchTreeTest {
public static void main(String[] args) {
//Object creation
BinarySearchTree<Integer> tree = new BinarySearchTree<>();
//Tree building...
tree.add2(50);
tree.add2(70);
tree.add2(80);
tree.add2(60);
tree.add2(30);
tree.add2(40);
tree.add2(20);
//Output tree
System.out.println("\nThe built binary search tree:");
System.out.println("\n" + tree.toString());
System.out.println("\nSearch the node with data 60: " + tree.find2(60));
System.out.println("Search the node with data 65: " + tree.find2(65));
System.out.println("Search the node with data 20: " + tree.find2(20));
System.out.println("Search the node with data 25: " + tree.find2(25));
}
}
我尝试到本地,将add2
方法调用更改为add2
而不是add
static class BinarySearchTree<Item extends Comparable> {
Node root;
boolean addReturn;
class Node {
Item data;
Node left;
Node right;
public Node(Item e) {
data = e;
}
}
public boolean add2(Item item) {
root = add2(root, item);
return addReturn;
}
private Node add2(Node localRoot, Item item) {
if (localRoot == null) {
// Adding item if tree is empty...
addReturn = true;
return new Node(item);
} else if (item.compareTo(localRoot.data) == 0) {
// Returning item if equal to root...
addReturn = false;
return localRoot;
} else if (item.compareTo(localRoot.data) < 0) {
// Adding item to right side of tree if less than the root...
localRoot.right = add2(localRoot.right, item);
return localRoot;
} else {
// Adding item to left side of tree if grater than the root...
localRoot.left = add2(localRoot.left, item);
return localRoot;
}
}
// wrapper method
public Item find2(Item target) {
return find2(root, target);
}
// recursive method
private Item find2(Node localRoot, Item target) {
if (localRoot == null) {
return null;
}
int compResult2 = target.compareTo(localRoot.data);
if (compResult2 == 0) {
return localRoot.data;
} else if (compResult2 < 0) {
return find2(localRoot.right, target);
} else {
return find2(localRoot.left, target);
}
}
}
public static void main(String[] args) {
// Object creation
BinarySearchTree<Integer> tree = new BinarySearchTree<>();
// Tree building...
tree.add2(50);
tree.add2(70);
tree.add2(80);
tree.add2(60);
tree.add2(30);
tree.add2(40);
tree.add2(20);
// Output tree
System.out.println("\nThe built binary search tree:");
System.out.println("\n" + tree.toString());
System.out.println("\nSearch the node with data 60: " + tree.find2(60));
System.out.println("Search the node with data 65: " + tree.find2(65));
System.out.println("Search the node with data 20: " + tree.find2(20));
System.out.println("Search the node with data 25: " + tree.find2(25));
}
,并给我输出:
Search the node with data 60: 60
Search the node with data 65: null
Search the node with data 20: 20
Search the node with data 25: null