Question

我一直试图找出为什么当我从测试人员类中调用它时，找不到我的countingLeaves方法。

我的编译器给了我错误TreeTester.java:25：错误：找不到符号 countLeaves（）; ^ 符号：方法countLeaves（） location：类TreeTester

    public class BinarySearchTree
{  
   private Node root;


   public BinarySearchTree()
   {  
      root = null;
   }


   public void add(Comparable obj) 
   {  
      Node newNode = new Node();
      newNode.data = obj;
      newNode.left = null;
      newNode.right = null;
      if (root == null) { root = newNode; }
      else { root.addNode(newNode); }
   }


   public boolean find(Comparable obj)
   {
      Node current = root;
      while (current != null)
      {
         int d = current.data.compareTo(obj);
         if (d == 0) { return true; }
         else if (d > 0) { current = current.left; }
         else { current = current.right; }
      }
      return false;
   }


   public void remove(Comparable obj)
   {


      Node toBeRemoved = root;
      Node parent = null;
      boolean found = false;
      while (!found && toBeRemoved != null)
      {
         int d = toBeRemoved.data.compareTo(obj);
         if (d == 0) { found = true; }
         else 
         {
            parent = toBeRemoved;
            if (d > 0) { toBeRemoved = toBeRemoved.left; }
            else { toBeRemoved = toBeRemoved.right; }
         }
      }

      if (!found) { return; }



      if (toBeRemoved.left == null || toBeRemoved.right == null)
      {
         Node newChild;
         if (toBeRemoved.left == null) 
         {
            newChild = toBeRemoved.right;
         }
         else 
         {
            newChild = toBeRemoved.left;
         }

         if (parent == null) // Found in root
         {
            root = newChild;
         }
         else if (parent.left == toBeRemoved)
         {
            parent.left = newChild;
         }
         else 
         {
            parent.right = newChild;
         }
         return;
      }



      Node smallestParent = toBeRemoved;
      Node smallest = toBeRemoved.right;
      while (smallest.left != null)
      {
         smallestParent = smallest;
         smallest = smallest.left;
      }



      toBeRemoved.data = smallest.data;
      if (smallestParent == toBeRemoved) 
      {
         smallestParent.right = smallest.right; 
      }
      else 
      {
         smallestParent.left = smallest.right; 
      }
   }


   public void print()
   {  
      print(root);
      System.out.println();
   }  


   private static void print(Node parent)
   {  
      if (parent == null) { return; }
      print(parent.left);
      System.out.print(parent.data + " ");
      print(parent.right);
   }

   public int countLeaves(Node node)
   {

      if(node == null)
         return 0;
      else if(node.left == null && node.right == null)
      {
         return 1;
      }
      else
      {
         return countLeaves(node.left) + countLeaves(node.right);
      }
   }


   class Node
   {  
      public Comparable data;
      public Node left;
      public Node right;


      public void addNode(Node newNode)
      {  
         int comp = newNode.data.compareTo(data);
         if (comp < 0)
         {  
            if (left == null) { left = newNode; }
            else { left.addNode(newNode); }
         }
         else if (comp > 0)
         {  
            if (right == null) { right = newNode; }
            else { right.addNode(newNode); }
         }
      }
   }
}

使用的测试人员类

public class TreeTester
{ 
   public static void main(String[] args)
   {  
      BinarySearchTree t = new BinarySearchTree();
      t.add("D");
      t.add("B");
      t.add("A");
      t.add("C");
      t.add("F");
      t.add("E");
      t.add("I");
      t.add("G");
      t.add("H");
      t.add("J");
      t.remove("A"); // Removing leaf
      t.remove("B"); // Removing element with one child
      t.remove("F"); // Removing element with two children
      t.remove("D"); // Removing root
      t.print();
      System.out.println("Expected: C E G H I J");
      countLeaves(t);
   }
}

Answer 1

countLeaves需要一个Node，而不是BinarySearchTree。

Answer 2

countLeaves需要Node，而不是BinarySearchTree。

您可以在BinarySearchTree中添加一个方法：

Node getRoot(){return root;}

Amd使用countLeaves(t.getRoot())。

计数在二叉树中的叶子

2 个答案: