compare_files.py

import os

with open('original', 'r') as o:
    original = set(o.readlines())

with open('report.txt', 'w') as report:
    for subdir, _, files in os.walk('submissions_462'):
        for f in files:
            with open(os.path.join(subdir, f), 'r') as file:
                s = set(file.readlines())
                report.write('{}: {}\n'.format(f, len(original & s)))