二叉树-找到二叉树中的最大搜索二叉子树

//找到二叉树中的最大搜索二叉子树
public class Node{
    public int value;
    public Node left;
    public Node right;

    public Node(int data){
        this.value=data;
    }
}
public Node biggestSubBST(Node head){
    int[] record=new int[3];
    return posOrder(head,record);
}
public Node posOrder(Node head,int[] record){
    if(head==null){
        record[0]=0;
        record[1]=Integer.MAX_VALUE;
        record[2]=Integer.MIN_VALUE;
        return null;
    }
    int value=head.value;
    Node left=head.left;
    Node right=head.right;
    Node lBST=posOrder(left,record);
    int lSize=record[0];
    int lMin=record[1];
    int lMax=record[2];
    Node rBST=posOrder(left,record);
    int rSize=record[0];
    int rMin=record[1];
    int rMax=record[2];
    record[1]=Math.min(lMin,value);
    record[2]=Math.max(rMax,value);
    if(left==lBST&&right==rBST&&lMax<value&&value<rMin){
        record[0]=lSize+rSize+1;
        return head;
    }
    record[0]=Math.max(lSize,rSize);
    return lSize>rSize?lBST:rBST;
}