Question

更新11:15 pm est 4/29/15 -

谢谢你帮助了很多人，几乎就在那里......

 public BinarySearchTree<AnyType> rebalanceHelp(ArrayList<AnyType> nl){
 BinarySearchTree<AnyType> p = new BinarySearchTree<AnyType>();
 //base case, if theres two elements in the list,   
 if(nl.size() == 2){p.insert(nl.get(0));p.insert(nl.get(1));}
  ArrayList<AnyType> left = new ArrayList<AnyType>();
  ArrayList<AnyType> right = new ArrayList<AnyType>();
  p.insert(nl.get(nl.size()/2));
  //loops through first half of the arraylist putting each element into a new arraylist, left
  for(int i = 1; i < ((nl.size()/2)-1); i++){
  left.add(nl.get(i));

  }
  //loops through second half of the arraylist putting each element into a new arraylist, right
  for(int j = nl.size()-1; j > ((nl.size()/2)+1); j--){
  right.add(nl.get(j));

  }
  //recursivley calls on left and right
  rebalanceHelp(left);rebalanceHelp(right);
      return p;
  }


public void rebalance(){
  //need a list of some sort (l) that i can resize and add to even if it is full 

  ArrayList<AnyType> l = new ArrayList<AnyType>();
  //ArrayList<AnyType> nl = new ArrayList<AnyType>();

  while(this.isEmpty() != true){
    l.add(this.findMin());
    this.removeMin();
   }
  this.rebalanceHelp(l);
}

现在收到错误：

DuplicateItemException: 8
at BinarySearchTree.insert(BinarySearchTree.java:171)
at BinarySearchTree.insert(BinarySearchTree.java:169)
at BinarySearchTree.insert(BinarySearchTree.java:78)
at BinarySearchTree.rebalanceHelp(BinarySearchTree.java:46)
at BinarySearchTree.rebalanceHelp(BinarySearchTree.java:58)
at BinarySearchTree.rebalanceHelp(BinarySearchTree.java:58)
at BinarySearchTree.rebalanceHelp(BinarySearchTree.java:58)
at BinarySearchTree.rebalance(BinarySearchTree.java:73)
at BinarySearchTree.main(BinarySearchTree.java:337)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at edu.rice.cs.drjava.model.compiler.JavacCompiler.runCommand(JavacCompiler.java:272)

问题在于我的递归方法中的for循环，对这些问题的任何帮助都会很棒，最后几个答案给了我很多洞察和理解。谢谢，亚光

Answer 1

这不是您通常如何平衡BST。当BST不平衡时，您可以通过旋转节点来修复它。这是一个代码来处理它的链接。 http://users.cis.fiu.edu/~weiss/dsaajava3/code/AvlTree.java

重新平衡二叉搜索树

1 个答案: