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LeetCode solutions

3934. Coupon Code Validator

My accepted Python solution to LeetCode problem 3934, Coupon Code Validator, running in 0ms.

  • Difficulty: Easy
  • Python
  • Runtime 0ms
  • Memory 17.5MB

Read the problem on LeetCode View on GitHub

The problem statement is LeetCode’s and stays on their site. What follows is my accepted solution.

Python

Accepted on LeetCode — runtime 0ms, memory 17.5MB, accepted 2025-12-30.

python
class Solution:
    def validateCoupons(self, code: List[str], businessLine: List[str], isActive: List[bool]) -> List[str]:
        valid_categories = {"electronics", "grocery", "pharmacy", "restaurant"}
        category_order = {"electronics": 0, "grocery": 1, "pharmacy": 2, "restaurant": 3}
        
        valid_coupons = []
        
        for i in range(len(code)):
            # Check if active
            if not isActive[i]:
                continue
            
            # Check if businessLine is valid
            if businessLine[i] not in valid_categories:
                continue
            
            # Check if code is non-empty and alphanumeric with underscores
            if not code[i]:
                continue
            
            is_valid_code = True
            for c in code[i]:
                if not (c.isalnum() or c == '_'):
                    is_valid_code = False
                    break
            
            if is_valid_code:
                valid_coupons.append((category_order[businessLine[i]], code[i]))
        
        # Sort by category first, then by code
        valid_coupons.sort()
        
        return [coupon[1] for coupon in valid_coupons]

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