rings.py

import sys

# https://classroom.google.com/c/NTU0OTE4MjA4NzMw/p/NTU1MjExNjY2MTI0/details
# CLI usage: python rings.py input.txt

routes = []
with open(sys.argv[1]) as file:
	routes = file.readlines()
	for i, route in enumerate(routes):
		routes[i] = route.rstrip()
		routes[i] = routes[i].split(" ")

		# Remove the first two entries (ID+1, R), which are useless metadata
		routes[i] = routes[i][2:]

# Remove the first line, which is useless since we're going to be using one file
# for each "dataset"
routes = routes[1:]

# Find minimum roundabout diameter
min = int(routes[0][0])
for route in routes:
	for roundabout in route:
		num = int(roundabout)
		if num < min:
			min = num

# Find routes that contain that diameter
congested = []
for i, route in enumerate(routes):
	for roundabout in route:
		if int(roundabout) == min:
			congested.append(i)
			break

# The output wants 1-based indices and not 0-based
for i, route in enumerate(congested):
	congested[i] += 1

# Convert congested to strings for output
for i, route in enumerate(congested):
	congested[i] = str(congested[i])

# Follow output format
print(min, "{%s}" % ','.join(congested))

• CBA to do user error handling
• Assumes input is ordered