HackerRank - 'Grep' - B

Problem:

N credit card numbers. Assume that the credit card numbers will have 4 space separated segments with 4 digits each.

# Input

• 1234 5678 9101 1234
• 2999 5178 9101 2234
• 9999 5628 9201 1232
• 8482 3678 9102 1232

# Output

• 1234 5678 9101 1234
• 2999 5178 9101 2234
• 9999 5628 9201 1232

# Solution

            
    grep '\(\d\)\s*\1'
    

Post:

• 2025-04 - Sed Command #3