題目摘要
從檔案裡篩選出電話號碼，電話號碼有兩種格式 (xxx) xxx-xxxx 和 xxx-xxx-xxxx。假設每行頭尾都沒有空格。

解法

注意

可問問題

原題
Given a text file file.txt that contains list of phone numbers (one per line), write a one liner bash script to print all valid phone numbers.

You may assume that a valid phone number must appear in one of the following two formats: (xxx) xxx-xxxx or xxx-xxx-xxxx. (x means a digit)

You may also assume each line in the text file must not contain leading or trailing white spaces.

For example, assume that file.txt has the following content:

987-123-4567
123 456 7890
(123) 456-7890

Your script should output the following valid phone numbers:

987-123-4567
(123) 456-7890