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46 lines
1.5 KiB
46 lines
1.5 KiB
7 years ago
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def graph_dfs(matrix):
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rows, cols = len(matrix), len(matrix[0])
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visited = set()
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directions = ((0, 1), (0, -1), (1, 0), (-1, 0))
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def dfs(i, j):
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if (i, j) in visited:
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return
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visited.add((i, j))
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# Traverse neighbors.
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for direction in directions:
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next_i, next_j = i + direction[0], j + direction[1]
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if 0 <= next_i < rows and 0 <= next_j < cols: # Check boundary.
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# Add any other checking here ^
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dfs(next_i, next_j)
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for i in range(rows):
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for j in range(cols):
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dfs(i, j)
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7 years ago
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# Follow up:
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# 1) Diagonal cells are considered neighbors
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# 2) View the matrix like Earth, right boundary is adjacent to the left boundary, top adjacent to left, etc.
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7 years ago
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def graph_dfs_diagonals_and_boundary_wrap(matrix):
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7 years ago
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rows, cols = len(matrix), len(matrix[0])
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visited = set()
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# Change 1: Add 4 more diagonal directions.
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directions = ((0, 1), (0, -1), (1, 0), (-1, 0), (-1, -1), (1, 1), (1, -1), (-1, 1))
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def dfs(i, j):
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if (i, j) in visited:
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return
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visited.add((i, j))
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for direction in directions:
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# Change 2: No more boundary, use modulo to allow traversal that exceed boundaries to wrap around.
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next_i, next_j = (i + direction[0] + rows) % rows, (j + direction[1] + cols) % cols
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dfs(next_i, next_j)
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for i in range(rows):
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for j in range(cols):
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dfs(i, j)
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7 years ago
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graph_dfs([
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[1, 2, 3, 4],
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[5, 6, 7, 8],
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[9, 10, 11, 12],
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])
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