Validating Credit Card Numbers in Python | HackerRank Solution

Hello coders, today we are going to solve Validating Credit Card Numbers HackerRank Solution in Python.

Task

You and Fredrick are good friends. Yesterday, Fredrick received N credit cards from ABCD Bank. He wants to verify whether his credit card numbers are valid or not. You happen to be great at regex so he is asking for your help!

A valid credit card from ABCD Bank has the following characteristics:

► It must start with a 4, 5 or 6.
► It must contain exactly 16 digits.
► It must only consist of digits (0-9).
► It may have digits in groups of 4, separated by one hyphen “-“.
► It must NOT use any other separator like ‘ ‘ , ‘_’, etc.
► It must NOT have 4 or more consecutive repeated digits.

Examples:

Valid Credit Card Numbers

4253625879615786
4424424424442444
5122-2368-7954-3214

Invalid Credit Card Numbers

42536258796157867       #17 digits in card number → Invalid 
4424444424442444        #Consecutive digits are repeating 4 or more times → Invalid
5122-2368-7954 - 3214   #Separators other than '-' are used → Invalid
44244x4424442444        #Contains non digit characters → Invalid
0525362587961578        #Doesn't start with 4, 5 or 6 → Invalid

Input Format

The first line of input contains an integer N.
The next N lines contain credit card numbers.

Constraints

• 0 < N < 100

Output Format

Print ‘Valid’ if the credit card number is valid. Otherwise, print ‘Invalid’. Do not print the quotes.

Sample Input

6
4123456789123456
5123-4567-8912-3456
61234-567-8912-3456
4123356789123456
5133-3367-8912-3456
5123 - 3567 - 8912 - 3456

Sample Output

Valid
Valid
Invalid
Valid
Invalid
Invalid

Explanation

4123456789123456 : Valid
5123-4567-8912-3456 : Valid
61234-567-8912-3456 : Invalid, because the card number is not divided into equal groups of .
4123356789123456 : Valid
51-33-33-67-8912-3456 : Invalid, consecutive digits 3333 is repeating 4 times.
5123456789123456 : Invalid, because space ‘  ‘ and - are used as separators.

Solution – Validating Credit Card Numbers in Python

# Enter your code here. Read input from STDIN. Print output to STDOUT
import re
n = int(input())
for t in range(n):
    credit = input().strip()
    credit_removed_hiphen = credit.replace('-','')
    valid = True
    length_16 = bool(re.match(r'^[4-6]\d{15}$',credit))
    length_19 = bool(re.match(r'^[4-6]\d{3}-\d{4}-\d{4}-\d{4}$',credit))    
    consecutive = bool(re.findall(r'(?=(\d)\1\1\1)',credit_removed_hiphen))
    if length_16 == True or length_19 == True:
        if consecutive == True:
            valid=False
    else:
        valid = False       
    if valid == True:
        print('Valid')
    else:
        print('Invalid')

Disclaimer: The above Problem (Validating Credit Card Numbers) is generated by Hacker Rank but the Solution is Provided by CodingBroz. This tutorial is only for Educational and Learning Purpose.