如何打印包含空值的二叉树的级别顺序遍历？爪哇

如何解决如何打印包含空值的二叉树的级别顺序遍历？爪哇

嘿伙计们，我正在尝试打印二叉树的级别顺序遍历，但我无法打印空值（在下面的代码中显示为连字符“-”）。你能帮我解决这个问题吗？到目前为止，这是我的代码：

static void printIt(Node root) {
    int h = findHeight(root);
    int i;
    for (i = 1; i <= h; i++)
        writeLevelOrder(root,i);
}


static int findHeight(Node node) {
    if (node == null) {
        return 0;
    }
    return 1 + Math.max(findHeight(node.right),findHeight(node.left));
}

static void writeLevelOrder(Node root,int level) {

    if (root==null) {
        System.out.print("- ");
        return;
    }

    if (level==1){
        System.out.print(root.val + " ");
    }
    else if (level > 1) {
        if (root.left == null) {
            System.out.print("- ");
        }
        if (root.right == null) {
            System.out.print("- ");
        }
        writeLevelOrder(root.left,level - 1);
        writeLevelOrder(root.right,level - 1);
    }
}

解决方法

这不是一个有效的解决方案，但它可以完成工作。我只是用 28282828 填充空值并在打印时检查它，这是我的解决方案：

static void printIt(Node root,BufferedWriter writer) throws IOException {
    int h = findHeight(root);
    int i;
    for (i = 1; i <= h; i++)
        writeLevelOrder(root,i,writer);
}


static int findHeight(Node node) {

    if (node == null) {
        return 0;
    }
    return 1 + Math.max(findHeight(node.right),findHeight(node.left));
}


static void writeLevelOrder(Node root,int level,BufferedWriter writer) throws IOException {


    if (root == null && level == 1) {
        System.out.print("- ");
        writer.write("- ");
        return;
    }
    if (root == null && level != 1) {
        Node r = new Node(28282828);
        root = r;
        root.left = r;
        root.right = r;
        System.out.print("- ");
        writer.write("- ");
    }
    if (root.val == 28282828 && level != 1) {
        System.out.print("- ");
        writer.write("- ");
    }
    if (level == 1 && root.val != 28282828) {
        System.out.print(root.val + " ");
        writer.write(root.val + " ");
    } else if (level > 1) {
        writeLevelOrder(root.left,level - 1,writer);
        writeLevelOrder(root.right,writer);

    }

}