二叉树的性质及其创建

// 统计叶子结点的个数
public int num_n0Node(BiTreeNode tree) { 
   
    if (tree.lchild==null && tree.rchild==null)
        return 1;
    if (tree == null)
        return 0;
    return num_n0Node(tree.lchild) + num_n0Node(tree.rchild);
}

// 求二叉树的深度
public int height(BiTreeNode tree) { 
   
    if (tree==null)
        return 0;
    int left = height(tree.lchild);
    int right = height(tree.rchild);
    return (left > right ? left : right) + 1;
}

// 打印树状二叉树
public void PrintBiTree(BiTreeNode tree, int nLayer) { 
   
    if (tree != null){ 
   
        PrintBiTree(tree.rchild, nLayer + 1);
        for (int i = 0; i < nLayer; i++)
            System.out.print(" ");  // 第几层data之前就空几个
        System.out.println(tree.data);
        PrintBiTree(tree.lchild, nLayer + 1);
    }
}

class BiTreeNode { 
   
    int data;   // 结点的信息
    BiTreeNode lchild, rchild;  // 左右孩子指针
}

public BiTreeNode Create() { 
   	// 先输入一个结点，已'#'代表null
    String s = scanner.nextLine();
    if ("#".equals(s))
        return null;
    int i = Integer.parseInt(s);
    BiTreeNode node = new BiTreeNode(i, Create(), Create());	// 创建结点，再递归创建它的左右结点
    return node;
}