这是一个家庭作业。我尝试在包含偶数数据值的树结构中查找节点数。以下是我在名为 LinkedTree 的 Java 类中的失败尝试。
public int numEvenKeys() {
return numEvenKeysTree(root);
}
private static int numEvenKeysTree(Node root) {
int num = 0;
if (root == null)
return 0;
else if (root.left != null || root.right != null)
return num + numEvenKeysTree(root.left)
+ numEvenKeysTree(root.right);
else if (root.key % 2 == 0)
num = 1;
return num;
}
这是我的主要课程的一部分：
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
LinkedTree tree = new LinkedTree();
tree.insert(7, "root node");
tree.insert(9, "7's right child");
tree.insert(5, "7's left child");
tree.insert(2, "5's left child");
tree.insert(8, "9's left child");
tree.insert(6, "5's right child");
tree.insert(4, "2's right child");
...
*** remove a node of your choice ***
...
System.out.print("number of nodes with even keys in this tree: ");
System.out.println(tree.numEvenKeys());
...
}
作为参考，这里是内部类节点和类构造函数：
private class Node {
private int key; // the key field
private LLList data; // the data items associated with this key
private Node left; // reference to the left child/subtree
private Node right; // reference to the right child/subtree
private Node parent; // reference to the parent
private Node(int key, Object data, Node left, Node right, Node parent){
this.key = key;
this.data = new LLList();
this.data.addItem(data, 0);
this.left = left;
this.right = right;
this.parent = parent;
}
private Node(int key, Object data) {
this(key, data, null, null, null);
}
}
// the root of the tree as a whole
private Node root;
public LinkedTree() {
root = null;
}
树的结构如下：
7
/ \
5 9
/ \ /
2 6 8
\
4
如果我选择删除节点7，该方法应该返回4。但是，它在我的实现中返回 1。有什么建议么？