76 lines
2.1 KiB
Python
76 lines
2.1 KiB
Python
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def count_guard_positions(map_lines):
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# Convert the map to a mutable 2D list of characters
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grid = [list(row) for row in map_lines]
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rows, cols = len(grid), len(grid[0])
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# Directions: UP=0, RIGHT=1, DOWN=2, LEFT=3
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directions = [(-1, 0), (0, 1), (1, 0), (0, -1)]
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# Find the initial guard position '^'
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start_pos = None
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for r in range(rows):
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for c in range(cols):
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if grid[r][c] == '^':
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start_pos = (r, c)
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grid[r][c] = '.' # Replace '^' with '.'
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break
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if start_pos:
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break
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# Initialize guard state
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current_pos = start_pos
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current_dir = 0 # Start facing UP
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visited = {current_pos}
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steps = 0
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# Large safety limit to prevent infinite loops in case something goes wrong
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max_steps = rows * cols * 10
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while True:
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steps += 1
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if steps > max_steps:
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# If something is wrong, break out to avoid infinite loop
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print("Exceeded maximum expected steps. Stopping.")
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break
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# Calculate the next forward position
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dr, dc = directions[current_dir]
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next_r = current_pos[0] + dr
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next_c = current_pos[1] + dc
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# Check if moving forward would leave the grid
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if not (0 <= next_r < rows and 0 <= next_c < cols):
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# The guard leaves the mapped area here
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break
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# Check if the next cell is an obstacle
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if grid[next_r][next_c] == '#':
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# Can't move forward, turn right
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current_dir = (current_dir + 1) % 4
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continue
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# The next cell is free, move forward
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current_pos = (next_r, next_c)
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visited.add(current_pos)
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# Continue forward in the same direction on the next iteration
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return len(visited)
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# Given example grid
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example_grid = [
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"....#.....",
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".........#",
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"..........",
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"..#.......",
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".......#..",
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"..........",
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".#.^......",
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"........#.",
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"#.........",
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"......#..."
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]
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result = count_guard_positions(example_grid)
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print("Result:", result)
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