二叉树中找到两个节点的最近公共祖先

import java.util.Ha
4000
shMap;
import java.util.HashSet;

/**
* Created by lxw, liwei4939@126.com on 2017/10/30.
* 二叉树中找到两个节点的最近公共祖先
*/
public class CommonAncestor {

public class Node{
int value;
Node left;
Node right;

public Node(int data){
this.value = data;
}
}

public Node lowestAncestor(Node head, Node n1, Node n2){
if(head == null || head == n1 || head == n2){
return head;
}
Node left = lowestAncestor(head.left, n1, n2);
Node right = lowestAncestor(head.right, n1, n2);
if(left != null && right != null){
return head;
}
return left != null ? left : right;
}

public class Record{
private HashMap<Node, Node> map = new HashMap<Node, Node>();
public Record(Node head){
if(head == null){
map.put(head, null);
}
setMap(head);
}

private void setMap(Node head){
if(head == null){
return;
}
if(head.left != null){
map.put(head.left, head);
}
if(head.right != null){
map.put(head.right, head);
}
setMap(head.left);
setMap(head.right);
}

public Node query(Node n1, Node n2){
HashSet<Node> set = new HashSet<Node>();
while (map.containsKey(n1)){
set.add(n1);
n1 = map.get(n1);
}
while (!set.contains(n2)){
n2 = map.get(n2);
}
}

}
}