50 lines
1.6 KiB
Python
50 lines
1.6 KiB
Python
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# Time: O(m*n)
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# Space: O(m*n)
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class Solution:
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def gameOfLife(self, board: List[List[int]]) -> None:
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"""
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Do not return anything, modify board in-place instead.
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"""
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nrows, ncols = len(board), len(board[0])
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board_copy = [[None] * ncols for _ in range(nrows)]
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for i in range(nrows):
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for j in range(ncols):
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board_copy[i][j] = next_cell_state(board, i, j)
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# Copy new board values
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for i in range(nrows):
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for j in range(ncols):
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board[i][j] = board_copy[i][j]
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def next_cell_state(board, i, j):
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current = board[i][j]
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total_alive = sum(get_cell_neighbours(board, i, j))
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# Rule 4: Exact 3 neighbors will mean dead cell becomes alive
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# Live cell remains live
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if total_alive == 3:
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return 1
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# Rule 2: Live cell lives onto next generation
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# Dead cell remains dead
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elif total_alive == 2:
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return current
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# Rules 1 and 2: Under-population and over-population
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return 0
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# Return cell at (i, j) or 0 if it's out of bounds
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def cell(board, i, j):
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nrows, ncols = len(board), len(board[0])
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return board[i][j] if 0 <= i < nrows and 0 <= j < ncols else 0
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# Get surrounding 8 neighbours of cell at (i, j)
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def get_cell_neighbours(board, i, j):
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return (
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cell(board, i - 1, j - 1), cell(board, i - 1, j), cell(board, i - 1, j + 1),
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cell(board, i, j - 1), cell(board, i, j + 1),
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cell(board, i + 1, j - 1), cell(board, i + 1, j), cell(board, i + 1, j + 1)
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)
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