Level Order Traversal

# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution(object):
    def levelOrder(self, root):
        """
        :type root: TreeNode
        :rtype: List[List[int]]
        """
        if(root==None):
            return
        queue=[root]
        result=[]
        while(queue):
            size=len(queue)
            level=[]
            for i in range(size):
                curr=queue.pop()
                level.append(curr.val)
                
                if(curr.left!=None):
                    queue=[curr.left]+queue
                
                if(curr.right!=None):
                    queue=[curr.right]+queue
            result.append(level)
        return result