FA-68661 / Toll and parking fee computation / Open access

One-way bridge toll with frequent-user discount: the discounted price is rounded to nearest · case 01

One-way bridge toll with frequent-user discount returns a wrong result when the discounted price is rounded to nearest.

Verified by executionVariant 1 · 8 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

Flooring the discount instead of the discounted price leaves the customer paying the fractional cent.

THE FAILURE

Flooring the discount instead of the discounted price leaves the customer paying the fractional cent.

Unsuccessful approach: Rounding to nearest also rounds up half the time.

Case contract

Input {trips: [[month index, direction, occupancy]], toll_dir, base, threshold, discount_pct, carpool_min}. Only trips in toll_dir are tolled. Carpools (occupancy >= carpool_min) are free and do not count. Paid trips are counted per month index (no carry-over between months); trips beyond threshold in a month pay floor(base*(100-discount)/100).

Why this case matters

Fee engines bill customers in integer cents; a wrong boundary, rounding stage or cap scope silently over- or under-charges.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    counts = {}
    total = 0
    for month, d, occ in x['trips']:
        if d != x['toll_dir']:
            continue
        if occ >= x['carpool_min']:
            continue
        k = counts.get(month, 0) + 1
        counts[month] = k
        if k > x['threshold']:
            total += x['base'] - x['base'] * x['discount_pct'] // 100
        else:
            total += x['base']
    return total
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[({'trips': [[1, 'W', 4], [2, 'W', 4], [1, 'E', 4], [1, 'E', 1], [1, 'W', 3], [2, 'W', 4], [1, 'E', 1], [2, 'E', 3], [1, 'W', 1], [13, 'W', 3]], 'toll_dir': 'E', 'base': 725, 'threshold': 1, 'discount_pct': 40, 'carpool_min': 3}, 1160), ({'trips': [[1, 'E', 1], [1, 'E', 1], [1, 'W', 1], [1, 'E', 2], [13, 'E', 3], [1, 'W', 4], [13, 'W', 3], [2, 'W', 3], [13, 'E', 1], [2, 'W', 1], [2, 'E', 1], [1, 'E', 4], [1, 'W', 1]], 'toll_dir': 'W', 'base': 850, 'threshold': 1, 'discount_pct': 25, 'carpool_min': 3}, 2337), ({'trips': [[2, 'W', 3], [1, 'W', 3], [1, 'E', 1], [2, 'E', 2], [2, 'W', 1], [1, 'E', 3], [1, 'W', 1], [13, 'W', 1]], 'toll_dir': 'W', 'base': 600, 'threshold': 1, 'discount_pct': 40, 'carpool_min': 3}, 1800), ({'trips': [[13, 'W', 3], [1, 'E', 2], [1, 'W', 1], [13, 'E', 1], [2, 'E', 3], [2, 'W', 1], [2, 'W', 1], [1, 'E', 3], [2, 'W', 1], [2, 'W', 3], [2, 'W', 1], [13, 'E', 1], [1, 'E', 1], [2, 'E', 3], [1, 'W', 2]], 'toll_dir': 'E', 'base': 725, 'threshold': 1, 'discount_pct': 25, 'carpool_min': 3}, 2536), ({'trips': [[1, 'W', 1], [1, 'W', 1], [1, 'W', 3], [1, 'W', 1], [13, 'W', 1]], 'toll_dir': 'W', 'base': 725, 'threshold': 2, 'discount_pct': 33, 'carpool_min': 3}, 2660), ({'trips': [[13, 'W', 3], [2, 'E', 4], [13, 'W', 2], [2, 'E', 2]], 'toll_dir': 'E', 'base': 600, 'threshold': 1, 'discount_pct': 33, 'carpool_min': 3}, 600), ({'trips': [[13, 'W', 3], [2, 'W', 1], [2, 'E', 3], [2, 'W', 3], [1, 'E', 1], [1, 'E', 2], [2, 'E', 1], [13, 'E', 4], [13, 'W', 1], [1, 'E', 1], [13, 'W', 3], [1, 'E', 3], [1, 'W', 1]], 'toll_dir': 'W', 'base': 850, 'threshold': 4, 'discount_pct': 33, 'carpool_min': 2}, 2550), ({'trips': [[2, 'W', 1], [1, 'E', 1], [1, 'E', 1], [1, 'E', 1], [13, 'E', 1], [1, 'E', 3], [13, 'E', 1], [2, 'W', 1]], 'toll_dir': 'W', 'base': 850, 'threshold': 5, 'discount_pct': 25, 'carpool_min': 2}, 1700)], [({'trips': [[13, 'E', 3], [13, 'W', 1], [2, 'W', 1], [1, 'E', 1], [1, 'E', 1], [2, 'W', 4], [13, 'E', 3], [1, 'W', 1], [1, 'W', 1], [1, 'W', 1], [2, 'W', 2], [13, 'E', 1], [1, 'W', 4], [13, 'W', 2], [1, 'E', 1], [2, 'W', 2]], 'toll_dir': 'W', 'base': 725, 'threshold': 1, 'discount_pct': 25, 'carpool_min': 2}, 3261), ({'trips': [[2, 'W', 1], [1, 'W', 3], [1, 'W', 3], [1, 'E', 1], [1, 'W', 4], [13, 'E', 2], [1, 'W', 3]], 'toll_dir': 'W', 'base': 600, 'threshold': 4, 'discount_pct': 40, 'carpool_min': 2}, 600), ({'trips': [[1, 'W', 1], [1, 'W', 1], [1, 'W', 3], [1, 'W', 1], [13, 'W', 1]], 'toll_dir': 'W', 'base': 725, 'threshold': 2, 'discount_pct': 33, 'carpool_min': 3}, 2660), ({'trips': [[1, 'W', 4], [2, 'E', 3], [2, 'W', 1], [2, 'E', 1]], 'toll_dir': 'E', 'base': 850, 'threshold': 3, 'discount_pct': 33, 'carpool_min': 2}, 850), ({'trips': [[1, 'W', 1], [1, 'E', 1], [1, 'E', 1], [1, 'E', 3], [1, 'W', 1], [2, 'E', 3], [1, 'E', 1], [2, 'W', 4], [1, 'E', 1], [13, 'E', 1], [2, 'E', 4], [2, 'W', 1], [1, 'E', 1]], 'toll_dir': 'W', 'base': 850, 'threshold': 1, 'discount_pct': 25, 'carpool_min': 2}, 2337), ({'trips': [[13, 'W', 1], [13, 'E', 1], [1, 'E', 1], [13, 'E', 3], [13, 'E', 4], [2, 'E', 1], [1, 'W', 1], [1, 'E', 1], [13, 'W', 1], [13, 'E', 1]], 'toll_dir': 'W', 'base': 850, 'threshold': 5, 'discount_pct': 25, 'carpool_min': 3}, 2550), ({'trips': [[1, 'E', 1], [13, 'W', 2], [2, 'E', 2], [1, 'W', 1], [1, 'E', 4], [2, 'W', 3], [13, 'W', 3], [2, 'W', 1], [1, 'W', 3], [1, 'W', 1], [13, 'W', 1], [1, 'E', 2], [13, 'E', 2], [1, 'E', 1]], 'toll_dir': 'E', 'base': 600, 'threshold': 1, 'discount_pct': 25, 'carpool_min': 2}, 1050), ({'trips': [[2, 'E', 1], [1, 'W', 1], [1, 'W', 4], [1, 'E', 1], [2, 'E', 2], [2, 'W', 2], [13, 'E', 1], [1, 'W', 4], [1, 'E', 2], [1, 'W', 1], [1, 'W', 1], [2, 'W', 3]], 'toll_dir': 'E', 'base': 600, 'threshold': 5, 'discount_pct': 33, 'carpool_min': 2}, 1800)], [({'trips': [[1, 'E', 1], [1, 'W', 1], [1, 'E', 4], [1, 'W', 3], [13, 'E', 1], [1, 'E', 2]], 'toll_dir': 'W', 'base': 725, 'threshold': 4, 'discount_pct': 40, 'carpool_min': 3}, 725), ({'trips': [[1, 'W', 4], [1, 'E', 1], [2, 'W', 3], [1, 'E', 2], [13, 'W', 2], [1, 'E', 4], [13, 'E', 1], [13, 'E', 1]], 'toll_dir': 'E', 'base': 725, 'threshold': 4, 'discount_pct': 25, 'carpool_min': 3}, 2900), ({'trips': [[1, 'W', 1], [1, 'W', 4], [2, 'W', 1], [2, 'E', 3], [1, 'E', 3], [1, 'E', 2], [2, 'W', 1], [1, 'W', 2], [13, 'E', 2], [1, 'E', 1], [1, 'E', 2], [13, 'E', 2], [13, 'E', 1], [1, 'W', 2], [13, 'W', 1]], 'toll_dir': 'W', 'base': 725, 'threshold': 1, 'discount_pct': 33, 'carpool_min': 3}, 3630), ({'trips': [[13, 'E', 2], [1, 'W', 3], [1, 'E', 4], [2, 'E', 1]], 'toll_dir': 'W', 'base': 600, 'threshold': 2, 'discount_pct': 33, 'carpool_min': 2}, 0), ({'trips': [[1, 'W', 1], [1, 'W', 2], [13, 'W', 4], [1, 'W', 4], [13, 'W', 3], [1, 'E', 4], [2, 'W', 2], [2, 'E', 1], [1, 'E', 4], [13, 'W', 1], [1, 'E', 1], [13, 'E', 1], [2, 'E', 1]], 'toll_dir': 'W', 'base': 850, 'threshold': 1, 'discount_pct': 33, 'carpool_min': 3}, 3119), ({'trips': [[2, 'W', 1], [1, 'W', 4], [13, 'E', 2], [2, 'E', 1], [13, 'W', 4], [2, 'E', 1], [2, 'E', 1], [1, 'W', 1], [1, 'W', 1], [1, 'E', 1], [13, 'W', 1], [1, 'E', 1], [2, 'E', 2], [1, 'W', 2]], 'toll_dir': 'W', 'base': 600, 'threshold': 1, 'discount_pct': 25, 'carpool_min': 2}, 2250), ({'trips': [[13, 'W', 1], [1, 'W', 2], [13, 'W', 1], [1, 'W', 3], [1, 'E', 4], [13, 'E', 1], [1, 'E', 1], [1, 'E', 2], [1, 'E', 1], [13, 'W', 1], [1, 'E', 1], [2, 'E', 2], [2, 'E', 3], [2, 'W', 3], [13, 'E', 1]], 'toll_dir': 'W', 'base': 850, 'threshold': 3, 'discount_pct': 33, 'carpool_min': 3}, 3400), ({'trips': [[1, 'W', 1], [1, 'W', 1], [1, 'W', 3], [1, 'W', 1], [13, 'W', 1]], 'toll_dir': 'W', 'base': 725, 'threshold': 2, 'discount_pct': 33, 'carpool_min': 3}, 2660)], [({'trips': [[1, 'W', 1], [1, 'W', 2], [1, 'W', 3], [13, 'W', 1], [13, 'W', 1], [1, 'E', 4], [13, 'W', 1], [13, 'E', 1], [13, 'E', 2], [2, 'W', 1]], 'toll_dir': 'W', 'base': 725, 'threshold': 1, 'discount_pct': 25, 'carpool_min': 2}, 3261), ({'trips': [[1, 'E', 1], [1, 'W', 3], [1, 'E', 2]], 'toll_dir': 'E', 'base': 725, 'threshold': 3, 'discount_pct': 33, 'carpool_min': 3}, 1450), ({'trips': [[1, 'E', 2], [1, 'E', 2], [1, 'E', 1], [2, 'E', 1], [2, 'W', 4], [13, 'W', 3], [1, 'E', 1], [1, 'W', 1], [2, 'W', 1]], 'toll_dir': 'W', 'base': 725, 'threshold': 4, 'discount_pct': 33, 'carpool_min': 2}, 1450), ({'trips': [[1, 'W', 1], [1, 'W', 1], [1, 'W', 3], [1, 'W', 1], [13, 'W', 1]], 'toll_dir': 'W', 'base': 725, 'threshold': 2, 'discount_pct': 33, 'carpool_min': 3}, 2660), ({'trips': [[2, 'W', 2], [2, 'E', 2], [1, 'E', 2], [2, 'E', 3], [1, 'W', 1], [1, 'E', 1], [13, 'E', 1], [1, 'W', 2], [1, 'E', 2], [1, 'W', 1], [2, 'W', 1], [13, 'E', 3], [1, 'E', 1], [13, 'W', 4], [1, 'W', 1]], 'toll_dir': 'W', 'base': 725, 'threshold': 1, 'discount_pct': 33, 'carpool_min': 3}, 3390), ({'trips': [[2, 'E', 2], [13, 'W', 1], [13, 'W', 3], [13, 'W', 4], [1, 'E', 3], [13, 'W', 1], [13, 'E', 2], [1, 'W', 2], [1, 'W', 3]], 'toll_dir': 'W', 'base': 600, 'threshold': 2, 'discount_pct': 33, 'carpool_min': 3}, 1800), ({'trips': [[13, 'E', 4], [2, 'W', 4], [13, 'W', 1], [13, 'W', 1], [2, 'E', 2], [2, 'E', 3], [13, 'E', 3], [13, 'E', 2]], 'toll_dir': 'W', 'base': 850, 'threshold': 3, 'discount_pct': 25, 'carpool_min': 2}, 1700), ({'trips': [[2, 'W', 1], [13, 'W', 1], [1, 'E', 1], [1, 'W', 1]], 'toll_dir': 'E', 'base': 725, 'threshold': 2, 'discount_pct': 40, 'carpool_min': 3}, 725)], [({'trips': [[1, 'W', 3], [1, 'E', 4], [1, 'W', 4]], 'toll_dir': 'E', 'base': 600, 'threshold': 1, 'discount_pct': 25, 'carpool_min': 3}, 0), ({'trips': [[1, 'E', 2], [1, 'E', 1], [1, 'W', 3], [1, 'W', 1], [13, 'E', 1], [1, 'E', 4], [2, 'E', 1], [1, 'W', 1], [1, 'E', 1], [1, 'E', 3], [13, 'E', 2], [13, 'E', 4], [13, 'E', 3]], 'toll_dir': 'W', 'base': 850, 'threshold': 1, 'discount_pct': 33, 'carpool_min': 3}, 1419), ({'trips': [[13, 'W', 3], [13, 'E', 4], [1, 'W', 3], [2, 'W', 1], [2, 'E', 4], [2, 'E', 1], [13, 'E', 1], [13, 'W', 4], [1, 'W', 1], [13, 'W', 1]], 'toll_dir': 'W', 'base': 600, 'threshold': 1, 'discount_pct': 25, 'carpool_min': 3}, 1800), ({'trips': [[1, 'E', 1], [1, 'E', 1], [2, 'E', 1], [2, 'E', 4], [2, 'E', 1], [2, 'E', 3], [1, 'W', 1], [1, 'W', 1], [1, 'W', 1], [1, 'W', 1]], 'toll_dir': 'E', 'base': 850, 'threshold': 4, 'discount_pct': 40, 'carpool_min': 2}, 3400), ({'trips': [[1, 'W', 1], [1, 'W', 1], [1, 'W', 3], [1, 'W', 1], [13, 'W', 1]], 'toll_dir': 'W', 'base': 725, 'threshold': 2, 'discount_pct': 33, 'carpool_min': 3}, 2660), ({'trips': [[2, 'E', 1], [2, 'E', 1], [1, 'W', 3], [1, 'W', 4], [1, 'E', 1], [1, 'E', 2], [2, 'W', 2], [13, 'E', 4], [1, 'W', 4], [1, 'W', 2], [1, 'E', 1], [1, 'W', 1]], 'toll_dir': 'E', 'base': 600, 'threshold': 5, 'discount_pct': 33, 'carpool_min': 2}, 2400), ({'trips': [[1, 'E', 1], [2, 'E', 4], [2, 'W', 3], [1, 'E', 1], [1, 'W', 4], [13, 'W', 1], [1, 'W', 2]], 'toll_dir': 'W', 'base': 600, 'threshold': 3, 'discount_pct': 33, 'carpool_min': 2}, 600), ({'trips': [[2, 'E', 3], [2, 'W', 1], [13, 'E', 1], [1, 'W', 2], [13, 'E', 4], [2, 'W', 3], [1, 'W', 1], [1, 'W', 4], [1, 'W', 1], [13, 'E', 1]], 'toll_dir': 'E', 'base': 725, 'threshold': 1, 'discount_pct': 33, 'carpool_min': 3}, 1210)]]
for i, (args, expected) in enumerate(fixtures[N-1]):
    check('fee oracle' + ' %d' % i, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
fee oracle 0	`1160`	`1160`	Passed
fee oracle 1	`2338`	`2337`	Failed
fee oracle 2	`1800`	`1800`	Passed
fee oracle 3	`2538`	`2536`	Failed
fee oracle 4	`2661`	`2660`	Failed
fee oracle 5	`600`	`600`	Passed
fee oracle 6	`2550`	`2550`	Passed
fee oracle 7	`1700`	`1700`	Passed

SHA-256 / 995a517a59bb8389510d1f9132f8d0c70630ed38d1f6d46199c2c073f6ee750b

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    counts = {}
    total = 0
    for month, d, occ in x['trips']:
        if d != x['toll_dir']:
            continue
        if occ >= x['carpool_min']:
            continue
        k = counts.get(month, 0) + 1
        counts[month] = k
        if k > x['threshold']:
            total += round(x['base'] * (100 - x['discount_pct']) / 100)
        else:
            total += x['base']
    return total
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[({'trips': [[1, 'W', 4], [2, 'W', 4], [1, 'E', 4], [1, 'E', 1], [1, 'W', 3], [2, 'W', 4], [1, 'E', 1], [2, 'E', 3], [1, 'W', 1], [13, 'W', 3]], 'toll_dir': 'E', 'base': 725, 'threshold': 1, 'discount_pct': 40, 'carpool_min': 3}, 1160), ({'trips': [[1, 'E', 1], [1, 'E', 1], [1, 'W', 1], [1, 'E', 2], [13, 'E', 3], [1, 'W', 4], [13, 'W', 3], [2, 'W', 3], [13, 'E', 1], [2, 'W', 1], [2, 'E', 1], [1, 'E', 4], [1, 'W', 1]], 'toll_dir': 'W', 'base': 850, 'threshold': 1, 'discount_pct': 25, 'carpool_min': 3}, 2337), ({'trips': [[2, 'W', 3], [1, 'W', 3], [1, 'E', 1], [2, 'E', 2], [2, 'W', 1], [1, 'E', 3], [1, 'W', 1], [13, 'W', 1]], 'toll_dir': 'W', 'base': 600, 'threshold': 1, 'discount_pct': 40, 'carpool_min': 3}, 1800), ({'trips': [[13, 'W', 3], [1, 'E', 2], [1, 'W', 1], [13, 'E', 1], [2, 'E', 3], [2, 'W', 1], [2, 'W', 1], [1, 'E', 3], [2, 'W', 1], [2, 'W', 3], [2, 'W', 1], [13, 'E', 1], [1, 'E', 1], [2, 'E', 3], [1, 'W', 2]], 'toll_dir': 'E', 'base': 725, 'threshold': 1, 'discount_pct': 25, 'carpool_min': 3}, 2536), ({'trips': [[1, 'W', 1], [1, 'W', 1], [1, 'W', 3], [1, 'W', 1], [13, 'W', 1]], 'toll_dir': 'W', 'base': 725, 'threshold': 2, 'discount_pct': 33, 'carpool_min': 3}, 2660), ({'trips': [[13, 'W', 3], [2, 'E', 4], [13, 'W', 2], [2, 'E', 2]], 'toll_dir': 'E', 'base': 600, 'threshold': 1, 'discount_pct': 33, 'carpool_min': 3}, 600), ({'trips': [[13, 'W', 3], [2, 'W', 1], [2, 'E', 3], [2, 'W', 3], [1, 'E', 1], [1, 'E', 2], [2, 'E', 1], [13, 'E', 4], [13, 'W', 1], [1, 'E', 1], [13, 'W', 3], [1, 'E', 3], [1, 'W', 1]], 'toll_dir': 'W', 'base': 850, 'threshold': 4, 'discount_pct': 33, 'carpool_min': 2}, 2550), ({'trips': [[2, 'W', 1], [1, 'E', 1], [1, 'E', 1], [1, 'E', 1], [13, 'E', 1], [1, 'E', 3], [13, 'E', 1], [2, 'W', 1]], 'toll_dir': 'W', 'base': 850, 'threshold': 5, 'discount_pct': 25, 'carpool_min': 2}, 1700)], [({'trips': [[13, 'E', 3], [13, 'W', 1], [2, 'W', 1], [1, 'E', 1], [1, 'E', 1], [2, 'W', 4], [13, 'E', 3], [1, 'W', 1], [1, 'W', 1], [1, 'W', 1], [2, 'W', 2], [13, 'E', 1], [1, 'W', 4], [13, 'W', 2], [1, 'E', 1], [2, 'W', 2]], 'toll_dir': 'W', 'base': 725, 'threshold': 1, 'discount_pct': 25, 'carpool_min': 2}, 3261), ({'trips': [[2, 'W', 1], [1, 'W', 3], [1, 'W', 3], [1, 'E', 1], [1, 'W', 4], [13, 'E', 2], [1, 'W', 3]], 'toll_dir': 'W', 'base': 600, 'threshold': 4, 'discount_pct': 40, 'carpool_min': 2}, 600), ({'trips': [[1, 'W', 1], [1, 'W', 1], [1, 'W', 3], [1, 'W', 1], [13, 'W', 1]], 'toll_dir': 'W', 'base': 725, 'threshold': 2, 'discount_pct': 33, 'carpool_min': 3}, 2660), ({'trips': [[1, 'W', 4], [2, 'E', 3], [2, 'W', 1], [2, 'E', 1]], 'toll_dir': 'E', 'base': 850, 'threshold': 3, 'discount_pct': 33, 'carpool_min': 2}, 850), ({'trips': [[1, 'W', 1], [1, 'E', 1], [1, 'E', 1], [1, 'E', 3], [1, 'W', 1], [2, 'E', 3], [1, 'E', 1], [2, 'W', 4], [1, 'E', 1], [13, 'E', 1], [2, 'E', 4], [2, 'W', 1], [1, 'E', 1]], 'toll_dir': 'W', 'base': 850, 'threshold': 1, 'discount_pct': 25, 'carpool_min': 2}, 2337), ({'trips': [[13, 'W', 1], [13, 'E', 1], [1, 'E', 1], [13, 'E', 3], [13, 'E', 4], [2, 'E', 1], [1, 'W', 1], [1, 'E', 1], [13, 'W', 1], [13, 'E', 1]], 'toll_dir': 'W', 'base': 850, 'threshold': 5, 'discount_pct': 25, 'carpool_min': 3}, 2550), ({'trips': [[1, 'E', 1], [13, 'W', 2], [2, 'E', 2], [1, 'W', 1], [1, 'E', 4], [2, 'W', 3], [13, 'W', 3], [2, 'W', 1], [1, 'W', 3], [1, 'W', 1], [13, 'W', 1], [1, 'E', 2], [13, 'E', 2], [1, 'E', 1]], 'toll_dir': 'E', 'base': 600, 'threshold': 1, 'discount_pct': 25, 'carpool_min': 2}, 1050), ({'trips': [[2, 'E', 1], [1, 'W', 1], [1, 'W', 4], [1, 'E', 1], [2, 'E', 2], [2, 'W', 2], [13, 'E', 1], [1, 'W', 4], [1, 'E', 2], [1, 'W', 1], [1, 'W', 1], [2, 'W', 3]], 'toll_dir': 'E', 'base': 600, 'threshold': 5, 'discount_pct': 33, 'carpool_min': 2}, 1800)], [({'trips': [[1, 'E', 1], [1, 'W', 1], [1, 'E', 4], [1, 'W', 3], [13, 'E', 1], [1, 'E', 2]], 'toll_dir': 'W', 'base': 725, 'threshold': 4, 'discount_pct': 40, 'carpool_min': 3}, 725), ({'trips': [[1, 'W', 4], [1, 'E', 1], [2, 'W', 3], [1, 'E', 2], [13, 'W', 2], [1, 'E', 4], [13, 'E', 1], [13, 'E', 1]], 'toll_dir': 'E', 'base': 725, 'threshold': 4, 'discount_pct': 25, 'carpool_min': 3}, 2900), ({'trips': [[1, 'W', 1], [1, 'W', 4], [2, 'W', 1], [2, 'E', 3], [1, 'E', 3], [1, 'E', 2], [2, 'W', 1], [1, 'W', 2], [13, 'E', 2], [1, 'E', 1], [1, 'E', 2], [13, 'E', 2], [13, 'E', 1], [1, 'W', 2], [13, 'W', 1]], 'toll_dir': 'W', 'base': 725, 'threshold': 1, 'discount_pct': 33, 'carpool_min': 3}, 3630), ({'trips': [[13, 'E', 2], [1, 'W', 3], [1, 'E', 4], [2, 'E', 1]], 'toll_dir': 'W', 'base': 600, 'threshold': 2, 'discount_pct': 33, 'carpool_min': 2}, 0), ({'trips': [[1, 'W', 1], [1, 'W', 2], [13, 'W', 4], [1, 'W', 4], [13, 'W', 3], [1, 'E', 4], [2, 'W', 2], [2, 'E', 1], [1, 'E', 4], [13, 'W', 1], [1, 'E', 1], [13, 'E', 1], [2, 'E', 1]], 'toll_dir': 'W', 'base': 850, 'threshold': 1, 'discount_pct': 33, 'carpool_min': 3}, 3119), ({'trips': [[2, 'W', 1], [1, 'W', 4], [13, 'E', 2], [2, 'E', 1], [13, 'W', 4], [2, 'E', 1], [2, 'E', 1], [1, 'W', 1], [1, 'W', 1], [1, 'E', 1], [13, 'W', 1], [1, 'E', 1], [2, 'E', 2], [1, 'W', 2]], 'toll_dir': 'W', 'base': 600, 'threshold': 1, 'discount_pct': 25, 'carpool_min': 2}, 2250), ({'trips': [[13, 'W', 1], [1, 'W', 2], [13, 'W', 1], [1, 'W', 3], [1, 'E', 4], [13, 'E', 1], [1, 'E', 1], [1, 'E', 2], [1, 'E', 1], [13, 'W', 1], [1, 'E', 1], [2, 'E', 2], [2, 'E', 3], [2, 'W', 3], [13, 'E', 1]], 'toll_dir': 'W', 'base': 850, 'threshold': 3, 'discount_pct': 33, 'carpool_min': 3}, 3400), ({'trips': [[1, 'W', 1], [1, 'W', 1], [1, 'W', 3], [1, 'W', 1], [13, 'W', 1]], 'toll_dir': 'W', 'base': 725, 'threshold': 2, 'discount_pct': 33, 'carpool_min': 3}, 2660)], [({'trips': [[1, 'W', 1], [1, 'W', 2], [1, 'W', 3], [13, 'W', 1], [13, 'W', 1], [1, 'E', 4], [13, 'W', 1], [13, 'E', 1], [13, 'E', 2], [2, 'W', 1]], 'toll_dir': 'W', 'base': 725, 'threshold': 1, 'discount_pct': 25, 'carpool_min': 2}, 3261), ({'trips': [[1, 'E', 1], [1, 'W', 3], [1, 'E', 2]], 'toll_dir': 'E', 'base': 725, 'threshold': 3, 'discount_pct': 33, 'carpool_min': 3}, 1450), ({'trips': [[1, 'E', 2], [1, 'E', 2], [1, 'E', 1], [2, 'E', 1], [2, 'W', 4], [13, 'W', 3], [1, 'E', 1], [1, 'W', 1], [2, 'W', 1]], 'toll_dir': 'W', 'base': 725, 'threshold': 4, 'discount_pct': 33, 'carpool_min': 2}, 1450), ({'trips': [[1, 'W', 1], [1, 'W', 1], [1, 'W', 3], [1, 'W', 1], [13, 'W', 1]], 'toll_dir': 'W', 'base': 725, 'threshold': 2, 'discount_pct': 33, 'carpool_min': 3}, 2660), ({'trips': [[2, 'W', 2], [2, 'E', 2], [1, 'E', 2], [2, 'E', 3], [1, 'W', 1], [1, 'E', 1], [13, 'E', 1], [1, 'W', 2], [1, 'E', 2], [1, 'W', 1], [2, 'W', 1], [13, 'E', 3], [1, 'E', 1], [13, 'W', 4], [1, 'W', 1]], 'toll_dir': 'W', 'base': 725, 'threshold': 1, 'discount_pct': 33, 'carpool_min': 3}, 3390), ({'trips': [[2, 'E', 2], [13, 'W', 1], [13, 'W', 3], [13, 'W', 4], [1, 'E', 3], [13, 'W', 1], [13, 'E', 2], [1, 'W', 2], [1, 'W', 3]], 'toll_dir': 'W', 'base': 600, 'threshold': 2, 'discount_pct': 33, 'carpool_min': 3}, 1800), ({'trips': [[13, 'E', 4], [2, 'W', 4], [13, 'W', 1], [13, 'W', 1], [2, 'E', 2], [2, 'E', 3], [13, 'E', 3], [13, 'E', 2]], 'toll_dir': 'W', 'base': 850, 'threshold': 3, 'discount_pct': 25, 'carpool_min': 2}, 1700), ({'trips': [[2, 'W', 1], [13, 'W', 1], [1, 'E', 1], [1, 'W', 1]], 'toll_dir': 'E', 'base': 725, 'threshold': 2, 'discount_pct': 40, 'carpool_min': 3}, 725)], [({'trips': [[1, 'W', 3], [1, 'E', 4], [1, 'W', 4]], 'toll_dir': 'E', 'base': 600, 'threshold': 1, 'discount_pct': 25, 'carpool_min': 3}, 0), ({'trips': [[1, 'E', 2], [1, 'E', 1], [1, 'W', 3], [1, 'W', 1], [13, 'E', 1], [1, 'E', 4], [2, 'E', 1], [1, 'W', 1], [1, 'E', 1], [1, 'E', 3], [13, 'E', 2], [13, 'E', 4], [13, 'E', 3]], 'toll_dir': 'W', 'base': 850, 'threshold': 1, 'discount_pct': 33, 'carpool_min': 3}, 1419), ({'trips': [[13, 'W', 3], [13, 'E', 4], [1, 'W', 3], [2, 'W', 1], [2, 'E', 4], [2, 'E', 1], [13, 'E', 1], [13, 'W', 4], [1, 'W', 1], [13, 'W', 1]], 'toll_dir': 'W', 'base': 600, 'threshold': 1, 'discount_pct': 25, 'carpool_min': 3}, 1800), ({'trips': [[1, 'E', 1], [1, 'E', 1], [2, 'E', 1], [2, 'E', 4], [2, 'E', 1], [2, 'E', 3], [1, 'W', 1], [1, 'W', 1], [1, 'W', 1], [1, 'W', 1]], 'toll_dir': 'E', 'base': 850, 'threshold': 4, 'discount_pct': 40, 'carpool_min': 2}, 3400), ({'trips': [[1, 'W', 1], [1, 'W', 1], [1, 'W', 3], [1, 'W', 1], [13, 'W', 1]], 'toll_dir': 'W', 'base': 725, 'threshold': 2, 'discount_pct': 33, 'carpool_min': 3}, 2660), ({'trips': [[2, 'E', 1], [2, 'E', 1], [1, 'W', 3], [1, 'W', 4], [1, 'E', 1], [1, 'E', 2], [2, 'W', 2], [13, 'E', 4], [1, 'W', 4], [1, 'W', 2], [1, 'E', 1], [1, 'W', 1]], 'toll_dir': 'E', 'base': 600, 'threshold': 5, 'discount_pct': 33, 'carpool_min': 2}, 2400), ({'trips': [[1, 'E', 1], [2, 'E', 4], [2, 'W', 3], [1, 'E', 1], [1, 'W', 4], [13, 'W', 1], [1, 'W', 2]], 'toll_dir': 'W', 'base': 600, 'threshold': 3, 'discount_pct': 33, 'carpool_min': 2}, 600), ({'trips': [[2, 'E', 3], [2, 'W', 1], [13, 'E', 1], [1, 'W', 2], [13, 'E', 4], [2, 'W', 3], [1, 'W', 1], [1, 'W', 4], [1, 'W', 1], [13, 'E', 1]], 'toll_dir': 'E', 'base': 725, 'threshold': 1, 'discount_pct': 33, 'carpool_min': 3}, 1210)]]
for i, (args, expected) in enumerate(fixtures[N-1]):
    check('fee oracle' + ' %d' % i, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
fee oracle 0	`1160`	`1160`	Passed
fee oracle 1	`2338`	`2337`	Failed
fee oracle 2	`1800`	`1800`	Passed
fee oracle 3	`2538`	`2536`	Failed
fee oracle 4	`2661`	`2660`	Failed
fee oracle 5	`600`	`600`	Passed
fee oracle 6	`2550`	`2550`	Passed
fee oracle 7	`1700`	`1700`	Passed

SHA-256 / 523c3394f022759c60aa526c3670dc3c91311d7bc3d46249d287c65cdb5f5869

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 8 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

Member access is invitation-based. Sign in with your invited account to inspect the repair.

Verification & scope

A deterministic, bounded toy model with a stipulated contract; it makes no claim of conformance to any agency manual or standard. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:48:04.321184+00:00.

Case digest / ed6971311fe537418206609864334dd80175b7fb342c10b1ac631c92c7c48c69