FA-68651 / Toll and parking fee computation / Open access

One-way bridge toll with frequent-user discount: the frequency counter never resets between months · case 01

One-way bridge toll with frequent-user discount returns a wrong result when the frequency counter never resets between months.

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

ROOT CAUSE

Trips from earlier months count toward the discount threshold.

THE FAILURE

Trips from earlier months count toward the discount threshold.

Unsuccessful approach: Folding month indices modulo 12 merges the same month of different years into one counter.

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 = sum(counts.values()) + 1
        counts[month] = counts.get(month, 0) + 1
        if k > x['threshold']:
            total += 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', 1], [2, 'W', 2], [2, 'W', 4], [1, 'E', 4], [2, 'E', 1]], 'toll_dir': 'W', 'base': 725, 'threshold': 2, 'discount_pct': 40, 'carpool_min': 2}, 725), ({'trips': [[1, 'E', 4], [2, 'E', 1], [1, 'E', 3], [1, 'E', 1], [1, 'W', 4], [2, 'W', 1], [13, 'E', 1], [1, 'W', 2], [1, 'E', 3], [1, 'W', 3], [13, 'W', 1], [2, 'E', 1]], 'toll_dir': 'W', 'base': 600, 'threshold': 5, 'discount_pct': 25, 'carpool_min': 3}, 1800), ({'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, 'E', 2], [1, 'W', 1], [2, 'W', 2], [1, 'E', 1], [2, 'W', 1], [13, 'E', 1], [13, 'W', 4], [13, 'W', 1], [1, 'E', 1], [1, 'E', 1]], 'toll_dir': 'E', 'base': 850, 'threshold': 2, 'discount_pct': 40, 'carpool_min': 3}, 3910), ({'trips': [[1, 'E', 4], [1, 'W', 3], [1, 'W', 2]], 'toll_dir': 'W', 'base': 725, 'threshold': 3, 'discount_pct': 33, 'carpool_min': 2}, 0), ({'trips': [[13, 'E', 3], [1, 'E', 4], [1, 'E', 1], [1, 'W', 3], [2, 'W', 4], [2, 'E', 1], [13, 'W', 1]], 'toll_dir': 'E', 'base': 850, 'threshold': 5, 'discount_pct': 40, 'carpool_min': 3}, 1700), ({'trips': [[13, 'W', 1], [1, 'E', 1], [2, 'W', 1], [13, 'E', 2], [1, 'W', 1], [1, 'W', 1], [1, 'W', 2], [13, 'W', 1], [1, 'E', 2], [13, 'W', 1], [2, 'E', 1], [1, 'W', 2], [1, 'W', 2], [13, 'W', 1], [2, 'W', 1]], 'toll_dir': 'E', 'base': 725, 'threshold': 1, 'discount_pct': 33, 'carpool_min': 3}, 2660), ({'trips': [[1, 'W', 3], [2, 'E', 2], [2, 'W', 1], [13, 'W', 1], [1, 'W', 1], [2, 'E', 1], [13, 'W', 1], [2, 'E', 1], [13, 'W', 3], [2, 'E', 1]], 'toll_dir': 'W', 'base': 850, 'threshold': 5, 'discount_pct': 40, 'carpool_min': 2}, 3400)], [({'trips': [[13, 'W', 4], [2, 'E', 1], [1, 'W', 1], [13, 'W', 1], [13, 'W', 1], [1, 'W', 4], [1, 'E', 3], [13, 'E', 1], [13, 'E', 4], [1, 'W', 4], [13, 'E', 1], [1, 'E', 2], [13, 'E', 4], [1, 'E', 1], [1, 'E', 4], [2, 'W', 3]], 'toll_dir': 'W', 'base': 600, 'threshold': 3, 'discount_pct': 33, 'carpool_min': 2}, 1800), ({'trips': [[1, 'E', 1], [1, 'E', 1], [1, 'W', 3], [2, 'E', 1], [1, 'W', 2], [13, 'W', 1], [13, 'E', 4], [2, 'E', 1], [1, 'W', 2], [2, 'W', 1], [13, 'W', 1], [13, 'W', 2], [13, 'E', 1], [2, 'E', 1]], 'toll_dir': 'E', 'base': 725, 'threshold': 2, 'discount_pct': 25, 'carpool_min': 3}, 4168), ({'trips': [[1, 'E', 1], [2, 'W', 2], [2, 'E', 1], [13, 'W', 1], [13, 'E', 3], [2, 'E', 1], [1, 'W', 1], [1, 'E', 2], [2, 'E', 1]], 'toll_dir': 'E', 'base': 600, 'threshold': 4, 'discount_pct': 40, 'carpool_min': 3}, 3000), ({'trips': [[13, 'E', 4], [2, 'E', 1], [1, 'E', 2], [2, 'E', 3], [1, 'W', 1], [1, 'E', 1], [1, 'E', 4]], 'toll_dir': 'W', 'base': 725, 'threshold': 4, 'discount_pct': 25, 'carpool_min': 3}, 725), ({'trips': [[13, 'W', 1], [1, 'W', 3], [1, 'W', 2], [13, 'E', 1], [13, 'E', 1], [2, 'E', 1], [13, 'W', 1], [1, 'W', 4], [1, 'E', 1], [1, 'W', 1], [1, 'W', 3]], 'toll_dir': 'W', 'base': 600, 'threshold': 2, 'discount_pct': 25, 'carpool_min': 3}, 2400), ({'trips': [[2, 'E', 1], [2, 'E', 4], [13, 'E', 1]], 'toll_dir': 'E', 'base': 850, 'threshold': 3, 'discount_pct': 40, 'carpool_min': 2}, 1700), ({'trips': [[1, 'E', 4], [13, 'W', 4], [1, 'E', 4], [13, 'W', 1], [1, 'W', 4], [1, 'E', 4], [13, 'W', 1], [13, 'W', 2], [1, 'E', 1], [13, 'W', 2], [13, 'E', 3], [1, 'E', 2], [2, 'E', 4], [1, 'E', 1], [1, 'W', 4]], 'toll_dir': 'E', 'base': 600, 'threshold': 4, 'discount_pct': 40, 'carpool_min': 3}, 1800), ({'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', 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, 'W', 4], [1, 'W', 1], [13, 'E', 1]], 'toll_dir': 'E', 'base': 600, 'threshold': 1, 'discount_pct': 33, 'carpool_min': 3}, 1200), ({'trips': [[1, 'W', 2], [13, 'E', 1], [2, 'W', 1], [1, 'W', 2], [2, 'E', 4], [13, 'W', 1], [13, 'W', 4], [13, 'E', 1], [2, 'W', 3], [1, 'E', 2], [13, 'E', 1]], 'toll_dir': 'W', 'base': 725, 'threshold': 3, 'discount_pct': 25, 'carpool_min': 2}, 1450), ({'trips': [[1, 'W', 1], [13, 'W', 3], [1, 'W', 1], [13, 'E', 4], [1, 'W', 1]], 'toll_dir': 'E', 'base': 600, 'threshold': 1, 'discount_pct': 25, 'carpool_min': 2}, 0), ({'trips': [[1, 'W', 1], [13, 'E', 1], [1, 'E', 3], [13, 'W', 1], [2, 'E', 4], [2, 'W', 1], [13, 'E', 4], [2, 'E', 2], [1, 'W', 1], [1, 'W', 1], [13, 'E', 1], [1, 'W', 1]], 'toll_dir': 'W', 'base': 725, 'threshold': 1, 'discount_pct': 33, 'carpool_min': 3}, 3630), ({'trips': [[2, 'E', 1], [1, 'W', 3], [13, 'E', 1], [13, 'W', 2]], 'toll_dir': 'E', 'base': 725, 'threshold': 2, 'discount_pct': 33, 'carpool_min': 3}, 1450), ({'trips': [[2, 'W', 1], [1, 'E', 1], [1, 'W', 1], [1, 'W', 1], [1, 'W', 2], [1, 'E', 2], [1, 'W', 1], [2, 'W', 1], [2, 'E', 1]], 'toll_dir': 'W', 'base': 600, 'threshold': 2, 'discount_pct': 40, 'carpool_min': 3}, 3120), ({'trips': [[13, 'E', 2], [1, 'W', 4], [1, 'W', 1], [1, 'W', 1], [1, 'E', 1], [2, 'W', 4], [2, 'E', 4], [1, 'W', 3], [13, 'E', 1], [13, 'W', 4], [1, 'W', 1]], 'toll_dir': 'W', 'base': 725, 'threshold': 1, 'discount_pct': 40, 'carpool_min': 3}, 1595)], [({'trips': [[2, 'W', 1], [1, 'W', 1], [13, 'W', 1], [13, 'W', 2], [2, 'E', 2], [1, 'W', 1], [1, 'W', 1], [2, 'E', 1], [1, 'E', 2], [2, 'E', 1], [2, 'W', 4], [1, 'W', 1], [13, 'E', 2], [1, 'E', 2], [13, 'E', 4], [1, 'W', 2]], 'toll_dir': 'W', 'base': 600, 'threshold': 5, 'discount_pct': 33, 'carpool_min': 3}, 4800), ({'trips': [[13, 'E', 1], [1, 'E', 1], [1, 'E', 1], [1, 'W', 1], [2, 'E', 2], [13, 'W', 1], [1, 'W', 1], [1, 'W', 3]], 'toll_dir': 'W', 'base': 725, 'threshold': 4, 'discount_pct': 33, 'carpool_min': 3}, 2175), ({'trips': [[1, 'W', 2], [1, 'E', 4], [1, 'W', 2], [2, 'E', 1], [2, 'E', 2], [13, 'W', 4], [2, 'W', 1], [1, 'W', 2], [1, 'W', 1], [1, 'E', 3]], 'toll_dir': 'E', 'base': 850, 'threshold': 5, 'discount_pct': 40, 'carpool_min': 2}, 850), ({'trips': [[1, 'E', 4], [13, 'E', 1], [13, 'E', 3]], 'toll_dir': 'E', 'base': 850, 'threshold': 1, 'discount_pct': 40, 'carpool_min': 2}, 850), ({'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, 'E', 2], [1, 'E', 1], [1, 'W', 4], [13, 'W', 1], [1, 'E', 3], [13, 'E', 4], [1, 'E', 1], [1, 'E', 1], [13, 'W', 3], [13, 'E', 1], [13, 'W', 1], [1, 'E', 1], [2, 'E', 1], [1, 'W', 3]], 'toll_dir': 'E', 'base': 600, 'threshold': 1, 'discount_pct': 33, 'carpool_min': 2}, 3006), ({'trips': [[2, 'E', 1], [2, 'E', 1], [1, 'W', 2], [13, 'E', 4], [1, 'W', 1], [2, 'W', 3], [1, 'W', 1], [1, 'W', 3], [2, 'E', 3], [1, 'E', 2], [1, 'E', 1], [1, 'E', 1], [13, 'E', 3], [13, 'W', 3], [1, 'W', 2]], 'toll_dir': 'E', 'base': 600, 'threshold': 1, 'discount_pct': 33, 'carpool_min': 3}, 2406), ({'trips': [[1, 'E', 3], [1, 'E', 1], [13, 'W', 3], [2, 'E', 1], [2, 'E', 2], [1, 'E', 2], [2, 'E', 1], [13, 'E', 4], [2, 'E', 1]], 'toll_dir': 'W', 'base': 850, 'threshold': 4, 'discount_pct': 33, 'carpool_min': 2}, 0)], [({'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, 'E', 1], [13, 'E', 1], [13, 'W', 3], [2, 'E', 2], [1, 'E', 4], [2, 'E', 1], [13, 'W', 1], [1, 'E', 4]], 'toll_dir': 'W', 'base': 600, 'threshold': 2, 'discount_pct': 40, 'carpool_min': 3}, 600), ({'trips': [[1, 'E', 3], [1, 'W', 4], [13, 'E', 3], [1, 'E', 3], [13, 'E', 2], [1, 'E', 4]], 'toll_dir': 'E', 'base': 850, 'threshold': 4, 'discount_pct': 25, 'carpool_min': 3}, 850), ({'trips': [[2, 'E', 3], [2, 'W', 1], [2, 'W', 2], [2, 'E', 1], [1, 'W', 1], [1, 'E', 4]], 'toll_dir': 'W', 'base': 725, 'threshold': 2, 'discount_pct': 25, 'carpool_min': 2}, 1450), ({'trips': [[1, 'E', 2], [1, 'E', 2], [1, 'E', 2], [1, 'W', 2], [1, 'E', 4], [2, 'W', 3], [2, 'W', 2], [1, 'E', 4]], 'toll_dir': 'E', 'base': 725, 'threshold': 3, 'discount_pct': 33, 'carpool_min': 3}, 2175), ({'trips': [[2, 'E', 4], [2, 'E', 2], [2, 'W', 1], [1, 'E', 1], [1, 'E', 2], [13, 'W', 2], [13, 'W', 3], [1, 'W', 1], [13, 'E', 1], [1, 'W', 1], [13, 'W', 1], [2, 'E', 1], [1, 'W', 3], [13, 'E', 2], [1, 'E', 1]], 'toll_dir': 'W', 'base': 600, 'threshold': 1, 'discount_pct': 40, 'carpool_min': 3}, 2520), ({'trips': [[2, 'E', 1], [2, 'W', 1], [2, 'W', 2], [2, 'W', 1], [13, 'W', 1], [1, 'W', 1], [1, 'E', 1], [1, 'E', 1], [2, 'E', 1], [2, 'W', 1], [1, 'E', 4], [1, 'W', 1]], 'toll_dir': 'E', 'base': 725, 'threshold': 1, 'discount_pct': 33, 'carpool_min': 2}, 2420), ({'trips': [[13, 'E', 2], [1, 'W', 2], [1, 'E', 1], [1, 'W', 3], [1, 'E', 4], [1, 'E', 4], [1, 'W', 1], [1, 'W', 2], [1, 'E', 2], [1, 'W', 1], [2, 'W', 3], [1, 'E', 4], [1, 'E', 1], [1, 'W', 4], [13, 'E', 1]], 'toll_dir': 'E', 'base': 600, 'threshold': 1, 'discount_pct': 33, 'carpool_min': 2}, 1602)]]
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	`725`	`725`	Passed
fee oracle 1	`1800`	`1800`	Passed
fee oracle 2	`2420`	`2660`	Failed
fee oracle 3	`3230`	`3910`	Failed
fee oracle 4	`0`	`0`	Passed
fee oracle 5	`1700`	`1700`	Passed
fee oracle 6	`2180`	`2660`	Failed
fee oracle 7	`3400`	`3400`	Passed

SHA-256 / 5891f105c8368eaca59a1635e0047f78a1898466526f259e1de0efa8622985fc

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 % 12, 0) + 1
        counts[month] = k
        if k > x['threshold']:
            total += 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', 1], [2, 'W', 2], [2, 'W', 4], [1, 'E', 4], [2, 'E', 1]], 'toll_dir': 'W', 'base': 725, 'threshold': 2, 'discount_pct': 40, 'carpool_min': 2}, 725), ({'trips': [[1, 'E', 4], [2, 'E', 1], [1, 'E', 3], [1, 'E', 1], [1, 'W', 4], [2, 'W', 1], [13, 'E', 1], [1, 'W', 2], [1, 'E', 3], [1, 'W', 3], [13, 'W', 1], [2, 'E', 1]], 'toll_dir': 'W', 'base': 600, 'threshold': 5, 'discount_pct': 25, 'carpool_min': 3}, 1800), ({'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, 'E', 2], [1, 'W', 1], [2, 'W', 2], [1, 'E', 1], [2, 'W', 1], [13, 'E', 1], [13, 'W', 4], [13, 'W', 1], [1, 'E', 1], [1, 'E', 1]], 'toll_dir': 'E', 'base': 850, 'threshold': 2, 'discount_pct': 40, 'carpool_min': 3}, 3910), ({'trips': [[1, 'E', 4], [1, 'W', 3], [1, 'W', 2]], 'toll_dir': 'W', 'base': 725, 'threshold': 3, 'discount_pct': 33, 'carpool_min': 2}, 0), ({'trips': [[13, 'E', 3], [1, 'E', 4], [1, 'E', 1], [1, 'W', 3], [2, 'W', 4], [2, 'E', 1], [13, 'W', 1]], 'toll_dir': 'E', 'base': 850, 'threshold': 5, 'discount_pct': 40, 'carpool_min': 3}, 1700), ({'trips': [[13, 'W', 1], [1, 'E', 1], [2, 'W', 1], [13, 'E', 2], [1, 'W', 1], [1, 'W', 1], [1, 'W', 2], [13, 'W', 1], [1, 'E', 2], [13, 'W', 1], [2, 'E', 1], [1, 'W', 2], [1, 'W', 2], [13, 'W', 1], [2, 'W', 1]], 'toll_dir': 'E', 'base': 725, 'threshold': 1, 'discount_pct': 33, 'carpool_min': 3}, 2660), ({'trips': [[1, 'W', 3], [2, 'E', 2], [2, 'W', 1], [13, 'W', 1], [1, 'W', 1], [2, 'E', 1], [13, 'W', 1], [2, 'E', 1], [13, 'W', 3], [2, 'E', 1]], 'toll_dir': 'W', 'base': 850, 'threshold': 5, 'discount_pct': 40, 'carpool_min': 2}, 3400)], [({'trips': [[13, 'W', 4], [2, 'E', 1], [1, 'W', 1], [13, 'W', 1], [13, 'W', 1], [1, 'W', 4], [1, 'E', 3], [13, 'E', 1], [13, 'E', 4], [1, 'W', 4], [13, 'E', 1], [1, 'E', 2], [13, 'E', 4], [1, 'E', 1], [1, 'E', 4], [2, 'W', 3]], 'toll_dir': 'W', 'base': 600, 'threshold': 3, 'discount_pct': 33, 'carpool_min': 2}, 1800), ({'trips': [[1, 'E', 1], [1, 'E', 1], [1, 'W', 3], [2, 'E', 1], [1, 'W', 2], [13, 'W', 1], [13, 'E', 4], [2, 'E', 1], [1, 'W', 2], [2, 'W', 1], [13, 'W', 1], [13, 'W', 2], [13, 'E', 1], [2, 'E', 1]], 'toll_dir': 'E', 'base': 725, 'threshold': 2, 'discount_pct': 25, 'carpool_min': 3}, 4168), ({'trips': [[1, 'E', 1], [2, 'W', 2], [2, 'E', 1], [13, 'W', 1], [13, 'E', 3], [2, 'E', 1], [1, 'W', 1], [1, 'E', 2], [2, 'E', 1]], 'toll_dir': 'E', 'base': 600, 'threshold': 4, 'discount_pct': 40, 'carpool_min': 3}, 3000), ({'trips': [[13, 'E', 4], [2, 'E', 1], [1, 'E', 2], [2, 'E', 3], [1, 'W', 1], [1, 'E', 1], [1, 'E', 4]], 'toll_dir': 'W', 'base': 725, 'threshold': 4, 'discount_pct': 25, 'carpool_min': 3}, 725), ({'trips': [[13, 'W', 1], [1, 'W', 3], [1, 'W', 2], [13, 'E', 1], [13, 'E', 1], [2, 'E', 1], [13, 'W', 1], [1, 'W', 4], [1, 'E', 1], [1, 'W', 1], [1, 'W', 3]], 'toll_dir': 'W', 'base': 600, 'threshold': 2, 'discount_pct': 25, 'carpool_min': 3}, 2400), ({'trips': [[2, 'E', 1], [2, 'E', 4], [13, 'E', 1]], 'toll_dir': 'E', 'base': 850, 'threshold': 3, 'discount_pct': 40, 'carpool_min': 2}, 1700), ({'trips': [[1, 'E', 4], [13, 'W', 4], [1, 'E', 4], [13, 'W', 1], [1, 'W', 4], [1, 'E', 4], [13, 'W', 1], [13, 'W', 2], [1, 'E', 1], [13, 'W', 2], [13, 'E', 3], [1, 'E', 2], [2, 'E', 4], [1, 'E', 1], [1, 'W', 4]], 'toll_dir': 'E', 'base': 600, 'threshold': 4, 'discount_pct': 40, 'carpool_min': 3}, 1800), ({'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', 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, 'W', 4], [1, 'W', 1], [13, 'E', 1]], 'toll_dir': 'E', 'base': 600, 'threshold': 1, 'discount_pct': 33, 'carpool_min': 3}, 1200), ({'trips': [[1, 'W', 2], [13, 'E', 1], [2, 'W', 1], [1, 'W', 2], [2, 'E', 4], [13, 'W', 1], [13, 'W', 4], [13, 'E', 1], [2, 'W', 3], [1, 'E', 2], [13, 'E', 1]], 'toll_dir': 'W', 'base': 725, 'threshold': 3, 'discount_pct': 25, 'carpool_min': 2}, 1450), ({'trips': [[1, 'W', 1], [13, 'W', 3], [1, 'W', 1], [13, 'E', 4], [1, 'W', 1]], 'toll_dir': 'E', 'base': 600, 'threshold': 1, 'discount_pct': 25, 'carpool_min': 2}, 0), ({'trips': [[1, 'W', 1], [13, 'E', 1], [1, 'E', 3], [13, 'W', 1], [2, 'E', 4], [2, 'W', 1], [13, 'E', 4], [2, 'E', 2], [1, 'W', 1], [1, 'W', 1], [13, 'E', 1], [1, 'W', 1]], 'toll_dir': 'W', 'base': 725, 'threshold': 1, 'discount_pct': 33, 'carpool_min': 3}, 3630), ({'trips': [[2, 'E', 1], [1, 'W', 3], [13, 'E', 1], [13, 'W', 2]], 'toll_dir': 'E', 'base': 725, 'threshold': 2, 'discount_pct': 33, 'carpool_min': 3}, 1450), ({'trips': [[2, 'W', 1], [1, 'E', 1], [1, 'W', 1], [1, 'W', 1], [1, 'W', 2], [1, 'E', 2], [1, 'W', 1], [2, 'W', 1], [2, 'E', 1]], 'toll_dir': 'W', 'base': 600, 'threshold': 2, 'discount_pct': 40, 'carpool_min': 3}, 3120), ({'trips': [[13, 'E', 2], [1, 'W', 4], [1, 'W', 1], [1, 'W', 1], [1, 'E', 1], [2, 'W', 4], [2, 'E', 4], [1, 'W', 3], [13, 'E', 1], [13, 'W', 4], [1, 'W', 1]], 'toll_dir': 'W', 'base': 725, 'threshold': 1, 'discount_pct': 40, 'carpool_min': 3}, 1595)], [({'trips': [[2, 'W', 1], [1, 'W', 1], [13, 'W', 1], [13, 'W', 2], [2, 'E', 2], [1, 'W', 1], [1, 'W', 1], [2, 'E', 1], [1, 'E', 2], [2, 'E', 1], [2, 'W', 4], [1, 'W', 1], [13, 'E', 2], [1, 'E', 2], [13, 'E', 4], [1, 'W', 2]], 'toll_dir': 'W', 'base': 600, 'threshold': 5, 'discount_pct': 33, 'carpool_min': 3}, 4800), ({'trips': [[13, 'E', 1], [1, 'E', 1], [1, 'E', 1], [1, 'W', 1], [2, 'E', 2], [13, 'W', 1], [1, 'W', 1], [1, 'W', 3]], 'toll_dir': 'W', 'base': 725, 'threshold': 4, 'discount_pct': 33, 'carpool_min': 3}, 2175), ({'trips': [[1, 'W', 2], [1, 'E', 4], [1, 'W', 2], [2, 'E', 1], [2, 'E', 2], [13, 'W', 4], [2, 'W', 1], [1, 'W', 2], [1, 'W', 1], [1, 'E', 3]], 'toll_dir': 'E', 'base': 850, 'threshold': 5, 'discount_pct': 40, 'carpool_min': 2}, 850), ({'trips': [[1, 'E', 4], [13, 'E', 1], [13, 'E', 3]], 'toll_dir': 'E', 'base': 850, 'threshold': 1, 'discount_pct': 40, 'carpool_min': 2}, 850), ({'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, 'E', 2], [1, 'E', 1], [1, 'W', 4], [13, 'W', 1], [1, 'E', 3], [13, 'E', 4], [1, 'E', 1], [1, 'E', 1], [13, 'W', 3], [13, 'E', 1], [13, 'W', 1], [1, 'E', 1], [2, 'E', 1], [1, 'W', 3]], 'toll_dir': 'E', 'base': 600, 'threshold': 1, 'discount_pct': 33, 'carpool_min': 2}, 3006), ({'trips': [[2, 'E', 1], [2, 'E', 1], [1, 'W', 2], [13, 'E', 4], [1, 'W', 1], [2, 'W', 3], [1, 'W', 1], [1, 'W', 3], [2, 'E', 3], [1, 'E', 2], [1, 'E', 1], [1, 'E', 1], [13, 'E', 3], [13, 'W', 3], [1, 'W', 2]], 'toll_dir': 'E', 'base': 600, 'threshold': 1, 'discount_pct': 33, 'carpool_min': 3}, 2406), ({'trips': [[1, 'E', 3], [1, 'E', 1], [13, 'W', 3], [2, 'E', 1], [2, 'E', 2], [1, 'E', 2], [2, 'E', 1], [13, 'E', 4], [2, 'E', 1]], 'toll_dir': 'W', 'base': 850, 'threshold': 4, 'discount_pct': 33, 'carpool_min': 2}, 0)], [({'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, 'E', 1], [13, 'E', 1], [13, 'W', 3], [2, 'E', 2], [1, 'E', 4], [2, 'E', 1], [13, 'W', 1], [1, 'E', 4]], 'toll_dir': 'W', 'base': 600, 'threshold': 2, 'discount_pct': 40, 'carpool_min': 3}, 600), ({'trips': [[1, 'E', 3], [1, 'W', 4], [13, 'E', 3], [1, 'E', 3], [13, 'E', 2], [1, 'E', 4]], 'toll_dir': 'E', 'base': 850, 'threshold': 4, 'discount_pct': 25, 'carpool_min': 3}, 850), ({'trips': [[2, 'E', 3], [2, 'W', 1], [2, 'W', 2], [2, 'E', 1], [1, 'W', 1], [1, 'E', 4]], 'toll_dir': 'W', 'base': 725, 'threshold': 2, 'discount_pct': 25, 'carpool_min': 2}, 1450), ({'trips': [[1, 'E', 2], [1, 'E', 2], [1, 'E', 2], [1, 'W', 2], [1, 'E', 4], [2, 'W', 3], [2, 'W', 2], [1, 'E', 4]], 'toll_dir': 'E', 'base': 725, 'threshold': 3, 'discount_pct': 33, 'carpool_min': 3}, 2175), ({'trips': [[2, 'E', 4], [2, 'E', 2], [2, 'W', 1], [1, 'E', 1], [1, 'E', 2], [13, 'W', 2], [13, 'W', 3], [1, 'W', 1], [13, 'E', 1], [1, 'W', 1], [13, 'W', 1], [2, 'E', 1], [1, 'W', 3], [13, 'E', 2], [1, 'E', 1]], 'toll_dir': 'W', 'base': 600, 'threshold': 1, 'discount_pct': 40, 'carpool_min': 3}, 2520), ({'trips': [[2, 'E', 1], [2, 'W', 1], [2, 'W', 2], [2, 'W', 1], [13, 'W', 1], [1, 'W', 1], [1, 'E', 1], [1, 'E', 1], [2, 'E', 1], [2, 'W', 1], [1, 'E', 4], [1, 'W', 1]], 'toll_dir': 'E', 'base': 725, 'threshold': 1, 'discount_pct': 33, 'carpool_min': 2}, 2420), ({'trips': [[13, 'E', 2], [1, 'W', 2], [1, 'E', 1], [1, 'W', 3], [1, 'E', 4], [1, 'E', 4], [1, 'W', 1], [1, 'W', 2], [1, 'E', 2], [1, 'W', 1], [2, 'W', 3], [1, 'E', 4], [1, 'E', 1], [1, 'W', 4], [13, 'E', 1]], 'toll_dir': 'E', 'base': 600, 'threshold': 1, 'discount_pct': 33, 'carpool_min': 2}, 1602)]]
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	`725`	`725`	Passed
fee oracle 1	`1800`	`1800`	Passed
fee oracle 2	`2420`	`2660`	Failed
fee oracle 3	`3910`	`3910`	Passed
fee oracle 4	`0`	`0`	Passed
fee oracle 5	`1700`	`1700`	Passed
fee oracle 6	`2420`	`2660`	Failed
fee oracle 7	`3400`	`3400`	Passed

SHA-256 / 2486dcf8df8caecafd26476b3110a0f63259d0b5369e276848d0af861154ab1d

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 2026-09-29T14:48:04.183209+00:00.

Case digest / 0ad283beaad0e3496569360db8eb9dca77c8ce7b8a7db8aa18ececa08fcd612b