假设树的节点的data类型为int型，请实现两棵树是否相等的

public  class Test {
	private static boolean flag = true;

	public static void main(String [] args){
		//根据输入参数构建树
		//comparePre(root1, root2);

		System.out.println(flag);
	}

	public static void comparePre(Node root1, Node root2){
		if(root1.data != root2.data){
			flag = false;
			return;
		}
		compare(root1, root2);
	}

	public static void compare(Node n1, Node n2){
		if(!flag)
			return;
		if(nodeEqual(n1.left, n2.left) &&nodeEqual(n1.right, n2.right)){
			if(n1.left != null)
				compare(n1.left, n2.left);
			if(n1.right != null)
				compare(n1.right, n2.right);
		} else if(nodeEqual(n1.left, n2.right) && nodeEqual(n1.right, n2.left)){
			if(n1.left != null)
				compare(n1.left, n2.right);
			if(n1.right != null)
				compare(n1.right, n2.left);
		} else {
			flag = false;
		}
	}
	
	public static boolean nodeEqual(Node n1, Node n2){
		if(n1 == n2)
			return true;
		if(n1 != null && n2 != null){
			if(n1.equals(n2)){
				return true;
			} else {
				return false;
			}
		} else {
			return false;
		}
	}
}

class Node{
	int data;
	Node left;
	Node right;
	public Node(int data){
		this.data = data;
	}

	@Override
	public boolean equals(Object node){
		if(node == null)
			return false;
		Node nodeTemp = (Node) node;
		if(nodeTemp.data != data)
			return false;
		return true;
	}
}