package part7tree;

import java.util.ArrayList;

/**
 * 递归的方式依次返回二叉树的前序、中序、后序
 * Created by Dell on 2017年07月26日.
 */
public class TreeToSequence {
 public int[][] convert(TreeNode root) {
 int[][] res=new int[3][];
 ArrayList<Integer> pre=new ArrayList<Integer>();
 ArrayList<Integer> in=new ArrayList<Integer>();
 ArrayList<Integer> post=new ArrayList<Integer>();
 preOrder(root,pre);
 inOrder(root,in);
 postOrder(root,post);
 res[0]=transeArray(pre);
 res[1]=transeArray(in);
 res[2]=transeArray(post);
 return res;
 }

 private void preOrder(TreeNode root, ArrayList<Integer> pre) {
 if(root!=null){
 pre.add(root.val);
 preOrder(root.left,pre);
 preOrder(root.right,pre);
 }
 }
 private void inOrder(TreeNode root, ArrayList<Integer> in) {
 if(root!=null){
 inOrder(root.left,in);
 in.add(root.val);
 inOrder(root.right,in);
 }
 }
 private void postOrder(TreeNode root, ArrayList<Integer> post) {
 if(root!=null){
 postOrder(root.left,post);

 postOrder(root.right,post);
 post.add(root.val);
 }
 }
 private int[] transeArray(ArrayList<Integer> list){
 int[] res=new int[list.size()];
 int count=0;
 for(Integer i:list){
 res[count++]=i;
 }
 return res;
 }
}