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Random fact: In the Caribbean there are oysters that can climb trees. solution in Clear category for Break Rings by siebenschlaefer
import functools
import itertools
def break_rings(connected_rings):
"""Return the minimal number of rings to break to separate all rings."""
rings = functools.reduce(set.union, connected_rings)
for i in range(1, max(rings) + 1):
for x in itertools.combinations(rings, i):
if not any(
pair
for pair in connected_rings
if pair.isdisjoint(x)):
return i
return 0
if __name__ == '__main__':
# These "asserts" using only for self-checking
# and not necessary for auto-testing
assert break_rings(
({1, 2}, {2, 3}, {3, 4}, {4, 5}, {5, 6}, {4, 6})) == 3, "example"
assert break_rings(
({1, 2}, {1, 3}, {1, 4}, {2, 3}, {2, 4}, {3, 4})) == 3, "All to all"
assert break_rings(
({5, 6}, {4, 5}, {3, 4}, {3, 2}, {2, 1}, {1, 6})) == 3, "Chain"
assert break_rings(
({8, 9}, {1, 9}, {1, 2}, {2, 3}, {3, 4}, {4, 5}, {5, 6}, {6, 7},
{8, 7})) == 5, "Long chain"
Aug. 1, 2015
