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First solution in Speedy category for New Cities by zimnytam
def subnetworks(net, crushes):
crushes = set(crushes)
cities = 0
visited = set()
alive = {node for connection in net for node in connection
if node not in crushes}
for start in alive:
if start not in visited:
stack = {start}
while stack:
current = stack.pop()
visited |= {current}
for left, right in net:
if right == current:
left, right = right, left
if left == current and right not in visited | crushes:
stack |= {right}
cities += 1
return cities
if __name__ == '__main__':
#These "asserts" using only for self-checking and not necessary for auto-testing
assert subnetworks([
['A', 'B'],
['B', 'C'],
['C', 'D']
], ['B']) == 2, "First"
assert subnetworks([
['A', 'B'],
['A', 'C'],
['A', 'D'],
['D', 'F']
], ['A']) == 3, "Second"
assert subnetworks([
['A', 'B'],
['B', 'C'],
['C', 'D']
], ['C', 'D']) == 1, "Third"
print('Done! Check button is waiting for you!')
Jan. 24, 2018
