Problem 193: valid phone numbers

problems/193-valid-phone-numbers/file.txt

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+987-123-4567
+123 456 7890
+(123) 456-7890
+0(001) 345-0000

problems/193-valid-phone-numbers/main.sh

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+#!/bin/bash
+grep -E "^([[:digit:]]{3}-|\([[:digit:]]{3}\) )[[:digit:]]{3}-[[:digit:]]{4}$" file.txt

problems/193-valid-phone-numbers/readme.md

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+# 193. Valid Phone Numbers
+
+Given a text file file.txt that contains a 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.
+
+## 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
+```