广度优先遍历

二叉树的广度优先遍历

public void breadFirst(TreeNode root){
        Queue<TreeNode> queue = new ArrayDeque<TreeNode>();
        if(root!=null){
            queue.add(root);
            while(!queue.isEmpty()){
                TreeNode p = queue.poll();
                System.out.print(p.val);
                if(p.left!=null){
                    queue.offer(p.left);
                }
                if(p.right!=null){
                    queue.offer(p.right);
                }
            }
        }
    }