Highest_Cost_Scenario_Identification

Highest Cost Scenario Identification

Dataset Overview

The dabstep dataset models payment processing fees with these key files:

• fees.json: 1000 fee rules, each specifying conditions and fee parameters
• merchant_category_codes.csv: MCC descriptions (not exhaustive — fee rules may reference MCCs not in this file)
• manual.md: Domain definitions including ACI codes (A–G) and fee formula

Fee formula: fee = fixed_amount + rate * transaction_amount / 10000

Two Question Types

Type 1: Most Expensive MCC

"What is the most expensive MCC for a transaction of X euros, in general?"

Find which MCC(s) can incur the highest fee across all fee rules.

import json

with open('fees.json') as f:
    fees = json.load(f)

amount = 50  # transaction amount in euros

mcc_max_fee = {}
for rule in fees:
    mcc_list = rule['merchant_category_code']
    if not mcc_list:  # empty list means rule applies to all MCCs, skip for MCC ranking
        continue
    fee = rule['fixed_amount'] + rule['rate'] * amount / 10000
    for mcc in mcc_list:
        mcc_max_fee[mcc] = max(mcc_max_fee.get(mcc, 0), fee)

max_fee = max(mcc_max_fee.values())
result_mccs = sorted([mcc for mcc, f in mcc_max_fee.items() if f == max_fee])
# Output as comma-separated sorted list
print(', '.join(str(m) for m in result_mccs))

Critical: Do NOT filter MCCs against merchant_category_codes.csv. Some MCCs in fee rules (e.g., 3003, 7231) are absent from the description file but are valid and must be included in results.

Type 2: Most Expensive ACI

"For a credit transaction of X euros on [CardScheme], what would be the most expensive ACI?"

Find which ACI letter leads to the highest possible fee for the specified card scheme and credit type. Only filter by the explicitly given conditions (card_scheme, is_credit); take the maximum fee across all other conditions.

import json

with open('fees.json') as f:
    fees = json.load(f)

card_scheme = 'GlobalCard'   # exact match required
is_credit = True             # set False for debit
amount = 1                   # transaction amount in euros
ALL_ACIS = ['A', 'B', 'C', 'D', 'E', 'F', 'G']

aci_max_fee = {}
for rule in fees:
    # Filter by card scheme
    if rule['card_scheme'] != card_scheme:
        continue
    # Filter by credit status: null means applies to both credit and debit
    if rule['is_credit'] is not None and rule['is_credit'] != is_credit:
        continue

    fee = rule['fixed_amount'] + rule['rate'] * amount / 10000
    # Empty aci list means rule applies to ALL ACI values
    acis = rule['aci'] if rule['aci'] else ALL_ACIS
    for aci in acis:
        aci_max_fee[aci] = max(aci_max_fee.get(aci, 0), fee)

max_fee = max(aci_max_fee.values())
best_acis = sorted([a for a, f in aci_max_fee.items() if f == max_fee])
result = [best_acis[0]]   # wrap in list — required output format
print(result)             # prints e.g. ['C']

The final <answer> must look like: <answer>['C']</answer> — a Python list containing the single ACI letter.

Key Rules and Pitfalls

Null/Empty field semantics (from manual.md)

Common errors to avoid

1. Outputting fee amount instead of ACI letter — the answer is always a letter (C, B, etc.) wrapped in a list (['C']), never a fee value like 0.23 or 0.1494. The example <answer>0.23</answer> in task instructions is a generic format example only.
2. Outputting bare letter without list — always wrap in a list: ['C'] not just C, even if the question says "Answer must be just one letter". The question also says "Provide the response in a list even if there is only one value" — the list format takes precedence.
3. Filtering MCCs by merchant_category_codes.csv — wrong. Always use MCCs from fees.json directly.
4. Ignoring null is_credit rules for ACI questions — rules with is_credit: null apply to credit transactions and must be included.
5. Forgetting empty aci list — an empty aci list in a rule means it covers ALL ACIs; don't skip these rules.

"In general" interpretation

"Most expensive in general" means the worst-case maximum fee across all possible rule configurations. Only apply the filters explicitly given in the question (card_scheme, is_credit, transaction amount). All other rule fields (capture_delay, monthly_fraud_level, monthly_volume, etc.) are ignored — take the maximum fee achievable under any applicable rule.

Tie-breaking

When multiple ACIs or MCCs share the same maximum fee, return the one with the lowest alphabetical/numerical order. For ACI questions, sort the tied ACIs alphabetically and take the first: sorted(tied_list)[0].

Output Format

• MCC questions: Comma-separated sorted list of MCC integers, e.g., 3000, 3001, 3002
• ACI questions: Single letter wrapped in a Python list, e.g., ['C'] — the answer is the LETTER, not the fee amount

ACI answer examples:

• <answer>['C']</answer> ✓
• <answer>['B']</answer> ✓
• <answer>C</answer> ✗ (missing list)
• <answer>0.23</answer> ✗ (fee value, not letter)

ACI Reference (from manual.md)

Card Schemes in Dataset

GlobalCard, NexPay, SwiftCharge, TransactPlus