193.md

Valid Phone Numbers

Description

link

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Solution

See Code

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Code

O(n)

# Read from the file file.txt and output all valid phone numbers to stdout.
grep -P '^(\d{3}-|\(\d{3}\) )\d{3}-\d{4}$' file.txt
# sed -n -r '/^([0-9]{3}-|\([0-9]{3}\) )[0-9]{3}-[0-9]{4}$/p' file.txt
# awk '/^([0-9]{3}-|\([0-9]{3}\) )[0-9]{3}-[0-9]{4}$/' file.txt