26 lines
653 B
Python
26 lines
653 B
Python
import math
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def get_inversions(grid):
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inversions = 0
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for i in range(len(grid)):
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if grid[i] is 0:
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continue
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for j in range(i + 1, len(grid)):
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if grid[j] is not 0 and grid[i] > grid[j]:
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inversions += 1
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return inversions
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def odd(n):
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return (n % 2) != 0
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def solvable(grid):
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"""Return True if the puzzle is solvable or False if it's not."""
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size = int(math.sqrt(len(grid)))
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inversions = get_inversions(grid)
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if odd(size):
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return not odd(inversions)
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else:
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if odd(grid.index(0)):
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return not odd(inversions)
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return odd(inversions)
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