LeetCode #193: Valid Phone Numbers
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LeetCode #193: Valid Phone Numbers:
shell
# Read from the file file.txt and output all valid phone numbers to stdout.
grep -E '^\([0-9]{3}\) [0-9]{3}-[0-9]{4}$|^[0-9]{3}-[0-9]{3}-[0-9]{4}$' file.txtegrep is the easiest way to go. It is a bit hard to remember its syntax.
A bit more optimized, grouping alternations at the beginning:
shell
# Read from the file file.txt and output all valid phone numbers to stdout.
grep -E '^(\([0-9]{3}\) [0-9]{3}|[0-9]{3}-[0-9]{3})-[0-9]{4}$' file.txt