Practice Valid Phone Numbers

Read the task, work through the examples, and check your approach against the constraints. Use the original LeetCode task for coding and submissions.

Easy#193

LeetCode Problem

Valid Phone Numbers

Shell

Problem Statement

Write a one-line Bash command that reads file.txt and prints only lines matching either xxx-xxx-xxxx or (xxx) xxx-xxxx, where each x is a decimal digit. Input has one number per line and no leading or trailing whitespace. Preserve matching lines in input order. Practice approach: Use an extended regular expression anchored at both ends, with alternatives for the two complete formats. Escape literal parentheses and require the single space after a parenthesized area code. Partial matches must not accept extra digits or text.

Source: Valid Phone Numbers on LeetCode. Use the original task for its coding environment and submissions.

Examples

# Example 1

Input

222-333-4444
(444) 555-6666
222 333 4444
222-333-44444

Output

222-333-4444
(444) 555-6666

Explanation

Only the first two lines have an accepted complete format.

Constraints

One candidate phone number per line.

No leading or trailing whitespace.

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