Jake Pullen
93 lines
3.1 KiB
Python
93 lines
3.1 KiB
Python
import heapq
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with open(r'advent_of_code\2023\day_17\input.txt', 'r') as file:
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input = file.read()
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test_input = '''2413432311323
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3215453535623
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3255245654254
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3446585845452
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4546657867536
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1438598798454
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4457876987766
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3637877979653
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4654967986887
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4564679986453
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1224686865563
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2546548887735
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4322674655533'''
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# Read the input data from the file
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#input_data = test_input
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input_data = input
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# Split the input data into lines
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lines = input_data.split('\n')
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# Create a grid from the lines
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grid = [[char for char in row] for row in lines]
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# Get the number of rows and columns in the grid
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num_rows = len(grid)
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num_columns = len(grid[0])
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# Function to solve the problem
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def solve(part2):
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# Initialize the queue with the starting position and direction
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queue = [(0, 0, 0, -1, -1)]
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# Initialize the dictionary to store the minimum distance to each position
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min_distance = {}
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# While the queue is not empty
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while queue:
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# Pop the position with the smallest distance from the queue
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distance, row, column, direction, in_direction = heapq.heappop(queue)
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# If the position has already been visited
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if (row, column, direction, in_direction) in min_distance:
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continue
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# Update the minimum distance to the current position
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min_distance[(row, column, direction, in_direction)] = distance
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# For each possible move
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for i, (delta_row, delta_column) in enumerate([[-1, 0], [0, 1], [1, 0], [0, -1]]):
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# Calculate the new position and direction
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new_row = row + delta_row
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new_column = column + delta_column
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new_direction = i
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new_in_direction = 1 if new_direction != direction else in_direction + 1
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# Check if the move is not a reverse move
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is_not_reverse = ((new_direction + 2) % 4 != direction)
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# Check if the move is valid
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is_valid_part1 = (new_in_direction <= 3)
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is_valid_part2 = (new_in_direction <= 10 and (new_direction == direction or in_direction >= 4 or in_direction == -1))
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is_valid = is_valid_part2 if part2 else is_valid_part1
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# If the new position is inside the grid and the move is not a reverse move and the move is valid
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if 0 <= new_row < num_rows and 0 <= new_column < num_columns and is_not_reverse and is_valid:
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# Calculate the cost of the move
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cost = int(grid[new_row][new_column])
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# Add the new position to the queue
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heapq.heappush(queue, (distance + cost, new_row, new_column, new_direction, new_in_direction))
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# Initialize the answer with a large number
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answer = 1e9
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# For each position in the dictionary
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for (row, column, direction, in_direction), value in min_distance.items():
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# If the position is the bottom right corner of the grid
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if row == num_rows - 1 and column == num_columns - 1:
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# Update the answer
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answer = min(answer, value)
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# Return the answer
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return answer
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# Print the solution for part 1
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print(solve(False))
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# Print the solution for part 2
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print(solve(True)) |