cs61b lab10

运行结果：

Creating 2-node tree.
Testing parent().

Testing insertChild().  Adding two more nodes to the 2-node tree.
Adding two more nodes to the 4-node tree.
1132
2131
The tree looks like this:
1
  11
  12
  13
    131
    132
[The above sequence should be 1, 11, 12, 13, 131, 132.]

Testing removeLeaf().  Removing one node from 6-node tree.
Removing another node from 5-node tree.
Attempting to remove non-leaf node from 4-node tree.
  Operation should have no effect.
Attempting to remove invalid node from 4-node tree.
The tree looks like this:
1
  12
  13
    131
    132
[The above sequence should be 1, 12, 13, 131.]
Removing remaining nodes from 4-node tree.

part1：实现parent（）

 public TreeNode parent() throws InvalidNodeException {
    if(isValidNode()){
        if(this==myTree.root){
            return new SibTreeNode();
        }
        else{
            return this.parent;
        }
    }
    else{
        throw new InvalidNodeException();
    }
  }

part2：insertChild（）分的情况比较多，代码也调整了很久，也比较长。

 public void insertChild(Object item, int c) throws InvalidNodeException {
    if(isValidNode()){
        if(this.firstChild==null||!this.firstChild.valid){
            SibTreeNode treenode=new SibTreeNode(myTree,item);
            this.firstChild=treenode;
            treenode.parent=this;
            myTree.size++;
        }
        else{
            SibTreeNode node=this.firstChild;
            if(c==1){
                SibTreeNode newnode=new SibTreeNode(myTree,item);
                newnode.parent=this;
                newnode.nextSibling=node;
                this.firstChild=newnode;
                myTree.size++;
                    }
            else if(c<=this.children()){
            while(c>2){
                node=node.nextSibling;
                c--;
            }
            SibTreeNode newnode=new SibTreeNode(myTree,item);
            newnode.parent=this;
            newnode.nextSibling=node.nextSibling;
            node.nextSibling=newnode;
            myTree.size++;
        }
        else{
            while(node.nextSibling!=null){
                node=node.nextSibling;
            }
            SibTreeNode newnode=new SibTreeNode(myTree,item);
            newnode.parent=this;
            node.nextSibling=newnode;
            myTree.size++;
        }
        }
        
    }
    else{
        throw new InvalidNodeException();
    }
  }

part3：removeLeaf（）也是需要考虑leaf在child中的具体位置，分了几种情况。

public void removeLeaf() throws InvalidNodeException {
      if(isValidNode()){
    if(this.firstChild!=null&&this.firstChild.isValidNode())
        return;
    else{
        if(this==myTree.root){
            this.valid=false;
            myTree.size--;
        }
        else if(this==this.parent.firstChild){
         this.parent.firstChild=this.nextSibling;
         this.valid=false;
         myTree.size--;
     }
     else if(this.nextSibling==null||!this.nextSibling.isValidNode())
        {
         this.valid=false;
         myTree.size--;
        }
    else{
        SibTreeNode node=this.parent.firstChild;
        while(node.nextSibling!=this)
            node=node.nextSibling;
        node.nextSibling=this.nextSibling;
        this.valid=false;
        myTree.size--;
    }
  }
  }
      else{
          throw new InvalidNodeException();
      }
}