从二叉树C＃中删除

Question

嗨，我在从C＃中的二叉树中删除时遇到了一个小问题。 我不知道为什么，但是这段代码无法正常工作（调用remove方法后我的树没有改变）。 这是我的代码：

public class BinaryTree<T>
{
    public BinaryTree<T> Left, Right;
    public T Data;
    public BinaryTree()
    {
        this.Left = null;
        this.Right = null;
    }
}


public BinaryTree<T> FindNode(T value,ref BinaryTree<T> myTree)
{
    if (myTree == null) 
        return null;
    else
    {
        int result = Comparer<T>.Default.Compare(value, myTree.Data);
        if (result == 0)
            return myTree;
        else if (result > 0)
            return FindNode(value, ref myTree.Right);
        else if (result < 0)
            return FindNode(value, ref myTree.Left);
    }
    return myTree;
}

public void RemoveValue(T value,ref BinaryTree<T> myTree)
{
    BinaryTree<T> helper = new BinaryTree<T>();
    BinaryTree<T> MyTree = myTree;
    if (MyTree == null) return;
    MyTree =FindNode(value,ref MyTree);
    if (MyTree.Left == null || MyTree.Right == null)
        helper = MyTree;
    else
    {
        helper = MyTree.Left;
        while (helper.Right!=null)
            helper = helper.Right;
        MyTree.Data = helper.Data;
    }
    if (helper.Left == null)
        helper = helper.Right;
    else
        helper = helper.Left;
}

BinaryTree表示树中的每个节点。

Answer 1

这是对您的代码的一些小整理，其中包含有关我认为RemoveValue应该如何工作的建议。 我由您决定完成实施。

public class BinaryTree<T>
{
    public T Data;
    public BinaryTree<T> Left, Right;
    public BinaryTree()
    {
        this.Left = null;
        this.Right = null;
    }

    public static BinaryTree<T> FindNode(T value, BinaryTree<T> myTree)
    {
        if (myTree == null)
            return null;
        else
        {
            int result = Comparer<T>.Default.Compare(value, myTree.Data);
            if (result == 0)
                return myTree;
            else if (result > 0)
                return FindNode(value, myTree.Right);
            else if (result < 0)
                return FindNode(value, myTree.Left);
        }
        return myTree;
    }

    public static void RemoveValue(T value, ref BinaryTree<T> myTree)
    {
        if (myTree == null)
            return;
        BinaryTree<T> treeNodeToRemove = FindNode(value, myTree);

        // First case: The node to remove has a single subtree
        if(treeNodeToRemove.Left == null ^ treeNodeToRemove.Right == null)
        {
            // We need to change the Left||Right reference of our parent to us...
        }
        // Second case: Both subtrees are null
        else if (treeNodeToRemove.Left == null && treeNodeToRemove.Right == null)
        {
            // We need to change the reference of our parent to null
        }
        // Third case: Both subtrees are full
        else
        {
            // ...
        }
    }
}

另外，这里是我用来概述这三种情况的链接 。