Check if tree is symmetric based on BFS algorithm

sym_tree.groovy

class Node {
  def val
	def left
	def right
}


/*
     root
   A       B
     C  D
   F       E
*/
Node root = new Node()
root.val = 'val'
Node A = new Node()
A.val = 'A'
Node B = new Node()
B.val = 'B'
Node C = new Node()
C.val = 'C'
Node D = new Node()
D.val = 'D'
Node F = new Node()
F.val = 'F'
Node E = new Node()
E.val = 'E'

root.left = A
root.right = B
A.right = C
B.left = D
C.left = F
D.right = E

// breadth first search
def bfs(Node n) {
	Queue<Node> q = new LinkedList<Node>()
	q.offer(n)
	while( q.size() > 0 ) {
		Node e = q.poll()
		print "$e.val "
		if(e.left != null) q.offer(e.left)
		if(e.right != null) q.offer(e.right)
	}
}


//bfs(root)
is_sym(root)


def is_sym(Node root) {
	String leftSubTree = sym_bfs(root.left, "l", "r")
	String rightSubTree = sym_bfs(root.right, "r", "l")
	println "$leftSubTree vs $rightSubTree"
	print leftSubTree.equals(rightSubTree)
}

def sym_bfs(Node n, String leftMark, String rightMark) {
	StringBuilder str = new StringBuilder();
	Queue<Node> q = new LinkedList<Node>()
	q.offer(n)
	while( q.size() > 0 ) {
		Node e = q.poll()
		
		if(e.left != null) {
			str.append( leftMark)
			q.offer(e.left)
		}
		if(e.right != null) {
			str.append( rightMark )
			q.offer(e.right)
		} 
	}	
	return str.toString()
}