54 lines
1.6 KiB
Python
54 lines
1.6 KiB
Python
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from collections import deque
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def maybe_queue(row, col, game, q, seen):
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"""
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Add coordinate, (`row`, `col`), to the queue, `q`, as long as it exists in
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the map, `game`, and it is not already present in `seen`.
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"""
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if row >= 0 and row < len(game) and col >= 0 and col < len(game[0]):
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if game[row][col] == 'L' and (row, col) not in seen:
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q.append((row, col))
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def visit_island(row, col, game, seen):
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"""
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Starting at the coordinate, (`row`, `col`), in the map, `game`, visit all
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surrounding tiles marked as land by adding them to the `seen` set.
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"""
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q = deque()
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q.append((row, col))
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while q:
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row, col = q.popleft()
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seen.add((row, col))
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maybe_queue(row - 1, col, game, q, seen) # UP
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maybe_queue(row + 1, col, game, q, seen) # DOWN
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maybe_queue(row, col - 1, game, q, seen) # LEFT
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maybe_queue(row, col + 1, game, q, seen) # RIGHT
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def count_islands(game):
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"""
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Return the number of contiguous land tiles in the map, `game`.
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"""
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result = 0
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seen = set()
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for row in range(len(game)):
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for col in range(len(game[row])):
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if game[row][col] == 'L' and (row, col) not in seen:
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visit_island(row, col, game, seen)
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result += 1
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return result
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################################################################################
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# Tests
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################################################################################
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game = [
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"LWLWWW",
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"LLLWWW",
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"WWWLLW",
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]
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result = count_islands(game)
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print(result)
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assert result == 2
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print("Success!")
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