LeetCode-193: Valid Phone Numbers

193. Valid Phone Numbers

Solution

1grep -E '^\([0-9]{3}\) [0-9]{3}-[0-9]{4}$|^[0-9]{3}-[0-9]{3}-[0-9]{4}$' file.txt

Valid Phone Numbers Explanation

Correct Regular Expressions

Pattern for (xxx) xxx-xxxx:

1^\([0-9]{3}\) [0-9]{3}-[0-9]{4}$

Pattern for xxx-xxx-xxxx:

1^[0-9]{3}-[0-9]{3}-[0-9]{4}$

Example Workflow

Given the input file file.txt containing:

1987-123-4567
2123 456 7890
3(123) 456-7890
4text 123-456-7890
5(123) 456-7890 text

The command processes it as follows:

1grep -E '^\([0-9]{3}\) [0-9]{3}-[0-9]{4}$|^[0-9]{3}-[0-9]{3}-[0-9]{4}$' file.txt

Expected Output

1987-123-4567
2(123) 456-7890

Debugging and Attempts

Original Attempt

1grep -E '^\(\d{3}\) \d{3}-\d{4}$|^\d{3}-\d{3}-\d{4}$' file.txt

Failed due to incorrect digit matching.

Corrected Solution

1grep -E '^\([0-9]{3}\) [0-9]{3}-[0-9]{4}$|^[0-9]{3}-[0-9]{3}-[0-9]{4}$' file.txt

Uses [0-9] instead of \d for better compatibility.

Debugging Script

To verify line-by-line matching:

1while IFS= read -r line; do
2    echo "Checking: '$line'"
3    if echo "$line" | grep -E '^\([0-9]{3}\) [0-9]{3}-[0-9]{4}$|^[0-9]{3}-[0-9]{3}-[0-9]{4}$'; then
4        echo "Matched: $line"
5    else
6        echo "Not Matched: $line"
7    fi
8done < file.txt

Final Thoughts

This solution ensures correct pattern matching for valid phone numbers in the specified formats, using extended regex for better readability and compatibility.