/**
* Definition for binary tree
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
import java.util.ArrayList;
import java.util.Iterator;
import java.util.Collections;
public class Solution {
public ArrayList<ArrayList<Integer>> zigzagLevelOrder(TreeNode root) {
// Start typing your Java solution below
// DO NOT write main() function
ArrayList<ArrayList<Integer>> list = new ArrayList<ArrayList<Integer>>();
if(root == null)
return list;
ArrayList<TreeNode> current = new ArrayList<TreeNode>();
current.add(root);//makd current to head
ArrayList<TreeNode> nextlevel = new ArrayList<TreeNode>();
boolean direction = true;
while(current.size()!=0){
nextlevel = new ArrayList<TreeNode>();
ArrayList<Integer> temp = new ArrayList<Integer>();
for(Iterator<TreeNode> it = current.iterator(); it.hasNext();){
TreeNode node = it.next();
temp.add(node.val);//get value for temp
if(node.left != null){
nextlevel.add(node.left);
}
if(node.right != null){
nextlevel.add(node.right);
}
}
if(!direction)
Collections.reverse(temp);
//temp is a list as part of lists add to list
current = nextlevel;
direction =! direction;
list.add(temp);
}
return list;
}
}