3606. Coupon Code Validator

3606. Coupon Code Validator

Difficulty: Easy

Topics: Array, Hash Table, String, Sorting, Weekly Contest 457

You are given three arrays of length n that describe the properties of n coupons: code, businessLine, and isActive. The iᵗʰ coupon has:

• code[i]: a string representing the coupon identifier.
• businessLine[i]: a string denoting the business category of the coupon.
• isActive[i]: a boolean indicating whether the coupon is currently active.

A coupon is considered valid if all of the following conditions hold:

1. code[i] is non-empty and consists only of alphanumeric characters (a-z, A-Z, 0-9) and underscores (_).
2. businessLine[i] is one of the following four categories: "electronics", "grocery", "pharmacy", "restaurant".
3. isActive[i] is true.

Return an array of the codes of all valid coupons, sorted first by their businessLine in the order: "electronics", "grocery", "pharmacy", "restaurant", and then by code in lexicographical (ascending) order within each category.

Example 1:

• Input: code = ["SAVE20","","PHARMA5","SAVE@20"], businessLine = ["restaurant","grocery","pharmacy","restaurant"], isActive = [true,true,true,true]
• Output: ["PHARMA5","SAVE20"]
• Explanation:
  • First coupon is valid.
  • Second coupon has empty code (invalid).
  • Third coupon is valid.
  • Fourth coupon has special character @ (invalid).

Example 2:

• Input: Input: code = ["GROCERY15","ELECTRONICS_50","DISCOUNT10"], businessLine = ["grocery","electronics","invalid"], isActive = [false,true,true]
• Output: ["ELECTRONICS_50"]
• Explanation:
  • First coupon is inactive (invalid).
  • Second coupon is valid.
  • Third coupon has invalid business line (invalid).

Constraints:

• n == code.length == businessLine.length == isActive.length
• 1 <= n <= 100
• 0 <= code[i].length, businessLine[i].length <= 100
• code[i] and businessLine[i] consist of printable ASCII characters.
• isActive[i] is either true or false.

Hint:

1. Filter out any coupon where isActive[i] is false, code[i] is empty or contains non‑alphanumeric/underscore chars, or businessLine[i] is not in the allowed set
2. Store each remaining coupon as a pair (businessLine[i], code[i])
3. Define a priority map, e.g. {"electronics":0, "grocery":1, "pharmacy":2, "restaurant":3}
4. Sort the list of pairs by (priority[businessLine], code) and return the code values in order

Solution:

We need to filter and sort coupon data based on specific validation rules. Let me break down the requirements and implement a solution.

Approach:

I'll follow these steps:

1. Filter out invalid coupons using the three conditions
2. Map business lines to a priority order for sorting
3. Sort valid coupons first by business line priority, then by code
4. Return just the codes in the correct order

Let's implement this solution in PHP: 3606. Coupon Code Validator

<?php
/**
 * @param String[] $code
 * @param String[] $businessLine
 * @param Boolean[] $isActive
 * @return String[]
 */
function validateCoupons($code, $businessLine, $isActive) {
    ...
    ...
    ...
    /**
     * go to ./solution.php
     */
}

// Test cases
echo validateCoupons(["SAVE20","","PHARMA5","SAVE@20"], ["restaurant","grocery","pharmacy","restaurant"], [true,true,true,true]) . "\n";    // Output: ["PHARMA5","SAVE20"]
echo validateCoupons(["GROCERY15","ELECTRONICS_50","DISCOUNT10"], ["grocery","electronics","invalid"], [false,true,true]) . "\n";           // Output: ["ELECTRONICS_50"]
?>

Explanation:

1. Validation:

   • Check isActive[i] is true
   • Check businessLine[i] exists in our priority map
   • Check code[i] is non-empty and matches regex /^[a-zA-Z0-9_]+$/

2. Sorting:

   • Use usort() with a custom comparator
   • First compare by business line priority (electronics=0, grocery=1, etc.)
   • If priorities are equal, compare by code lexicographically using strcmp()

3. Return:

   • Extract only the code strings from the sorted array
   • Return as a simple array of strings

Complexity Analysis

• Time Complexity: O(n log n) due to sorting, where n is the number of valid coupons
• Space Complexity: O(n) for storing valid coupons

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