Corrected Algorithm and fix brand validation in credit.py #58
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WalkthroughRewrote Changes
Sequence Diagram(s)sequenceDiagram
autonumber
participant User
participant credit.py as Validator
participant Output
User->>Validator: provide card number (input -> str)
Note right of Validator: Single pass checksum\n(reverse per-digit loop)
Validator->>Validator: compute Luhn checksum (in-place)
Validator-->>Validator: derive validated flag (checksum % 10 == 0)
alt validated
Validator->>Validator: determine card type by length & prefix
Validator->>Output: print card type (AMEX/MASTERCARD/VISA)
else invalid
Validator->>Output: print "INVALID" and exit
end
Estimated code review effort🎯 3 (Moderate) | ⏱️ ~20 minutes
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Pre-merge checks and finishing touches✅ Passed checks (3 passed)
✨ Finishing touches
🧪 Generate unit tests (beta)
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🔇 Additional comments (6)
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⚠️ Outside diff range comments (1)
Week 6/Problem Set 6/Sentimental Credit More/credit.py (1)
1-24: Critical: Remove duplicate imports and validation block.Lines 1-24 contain the complete validation logic, but lines 22-24 duplicate the imports and are followed by another complete copy of the same validation block (lines 26-41). This appears to be a merge conflict or copy-paste error that makes the code execute the same validation twice.
Apply this diff to remove the duplication:
import sys from cs50 import get_int number = get_int("Number: ") # Store the first 1 and 2 digits of the credit card number entered beginning2 = int(str(number)[:2]) beginning1 = int(str(number)[:1]) # Check if the credit card is valid if not ( beginning2 == 34 or beginning2 == 37 or beginning1 == 4 or beginning1 == 5 or beginning1 == 6 ): print("INVALID") sys.exit() - -import sys - -from cs50 import get_int - -number = get_int("Number: ") - -# Store the first 1 and 2 digits of the credit card number entered -beginning2 = int(str(number)[:2]) -beginning1 = int(str(number)[:1]) - -# Check if the credit card is valid -if not ( - beginning2 == 34 - or beginning2 == 37 - or beginning1 == 4 - or beginning1 == 5 - or beginning1 == 6 -): - print("INVALID") - sys.exit() # Vars product = 0
🧹 Nitpick comments (1)
Week 6/Problem Set 6/Sentimental Credit More/credit.py (1)
64-69: Minor: Unused loop variable.The loop variable
ifromenumerateis not used in either loop. Usesum()for cleaner code or iterate withoutenumerate.Apply this diff:
-sumdigits = 0 -for i, item in enumerate(everyotherdig): - sumdigits += item - -othersum = 0 -for i, item in enumerate(others): - othersum += item +sumdigits = sum(everyotherdig) +othersum = sum(others)Based on static analysis hints.
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Week 6/Problem Set 6/Sentimental Credit More/credit.py(2 hunks)
🧰 Additional context used
🪛 Ruff (0.14.3)
Week 6/Problem Set 6/Sentimental Credit More/credit.py
64-64: Loop control variable i not used within loop body
(B007)
68-68: Loop control variable i not used within loop body
(B007)
🔇 Additional comments (1)
Week 6/Problem Set 6/Sentimental Credit More/credit.py (1)
84-106: Approve the brand detection logic structure.The card brand detection logic is correctly structured with appropriate checks for:
- AMEX: 34, 37 prefix
- MasterCard: 51-55 prefix
- Visa: 4 prefix
- Minimum length of 13 digits
However, this will only work correctly once the critical checksum validation bug (lines 77-81) is fixed.
1 participant
Fixed checksum logic, corrected brand detection rules, and removed redundant loops.
Summary by CodeRabbit
Bug Fixes
Refactor