102. Binary Tree Level Order Traversal

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public List<List<Integer>> levelOrder(TreeNode root) {
        List<List<Integer>> res=new ArrayList<List<Integer>>();
        if(root==null)
            return res;
        Queue<TreeNode> q=new LinkedList<TreeNode>();
        q.offer(root);
        int size=q.size();
        int count=0;
        List<Integer> templist=new ArrayList<Integer>();
        while(!q.isEmpty())
        {
            TreeNode temp=q.poll();
            if(temp.left!=null)
                q.offer(temp.left);
            if(temp.right!=null)
                q.offer(temp.right);
            count++;
            templist.add(temp.val);
            if(count==size)
            {
                size=q.size();
                count=0;
                res.add(templist);
                templist=new ArrayList<Integer>();
            }
        }
        return res;
        
    }
}