121 lines
3.6 KiB
Python
121 lines
3.6 KiB
Python
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import lib
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EXAMPLE = """
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Sabqponm
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abcryxxl
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accszExk
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acctuvwj
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abdefghi
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"""
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def neighbors_4(row, col, rows, cols):
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n = []
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for r, c in [(1, 0), (-1, 0), (0, 1), (0, -1)]:
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new_row, new_col = row + r, col + c
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if new_row >= 0 and new_row < rows and new_col >= 0 and new_col < cols:
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n.append((new_row, new_col))
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return n
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def solve(lines: list[str]):
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start = (0, 0)
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end = (0, 0)
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rows = len(lines)
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cols = len(lines[0])
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heights = []
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dists = []
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for (row, line) in enumerate(lines):
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heights.append([])
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dists.append([])
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for (col, c) in enumerate(line):
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if c == 'S':
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start = (row, col)
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heights[row].append(0)
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dists[row].append(0)
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elif c == 'E':
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end = (row, col)
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heights[row].append(26)
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dists[row].append(2**16)
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else:
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heights[row].append(ord(lines[row][col]) - ord('a'))
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dists[row].append(2**16)
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active_fields = [start]
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while active_fields:
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row, col = active_fields.pop()
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current_dist = dists[row][col]
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current_height = heights[row][col]
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for row, col in neighbors_4(row, col, rows, cols):
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pot_height = heights[row][col]
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if current_height < pot_height - 1:
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continue
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if current_dist + 1 < dists[row][col]:
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dists[row][col] = current_dist + 1
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active_fields.append((row, col))
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# for row in dists:
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# print(row)
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# 34:00
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return dists[end[0]][end[1]]
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def solve2(lines: list[str]):
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starts = []
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all_dists =[]
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for (row, line) in enumerate(lines):
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for (col, c) in enumerate(line):
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if c == 'S' or c == 'a':
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starts.append((row, col))
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for start in starts:
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end = (0, 0)
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rows = len(lines)
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cols = len(lines[0])
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heights = []
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dists = []
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for (row, line) in enumerate(lines):
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heights.append([])
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dists.append([])
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for (col, c) in enumerate(line):
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if row == start[0] and col == start[1]:
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heights[row].append(0)
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dists[row].append(0)
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elif c == 'E':
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end = (row, col)
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heights[row].append(26)
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dists[row].append(2**16)
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else:
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heights[row].append(ord(lines[row][col]) - ord('a'))
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dists[row].append(2**16)
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active_fields = [start]
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while active_fields:
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row, col = active_fields.pop()
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current_dist = dists[row][col]
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current_height = heights[row][col]
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for row, col in neighbors_4(row, col, rows, cols):
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pot_height = heights[row][col]
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if current_height < pot_height - 1:
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continue
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if current_dist + 1 < dists[row][col]:
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dists[row][col] = current_dist + 1
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active_fields.append((row, col))
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all_dists.append(dists[end[0]][end[1]])
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# 39:45
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return min(all_dists)
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def main():
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lines = lib.str_to_lines_no_empty(EXAMPLE)
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print("Example 1:", solve(lines))
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lines = lib.str_to_lines_no_empty(open("i12.txt").read())
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print("Solution 1:", solve(lines))
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lines = lib.str_to_lines_no_empty(EXAMPLE)
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print("Example 2:", solve2(lines))
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lines = lib.str_to_lines_no_empty(open("i12.txt").read())
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print("Solution 2:", solve2(lines))
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if __name__ == "__main__":
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main()
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