day 12 done

2023/day_12/part 2 solution.py

@@ -1,6 +1,90 @@
-import os
-
 with open(r'advent_of_code\2023\day_12\input.txt', 'r') as file:
-    input = file.read()
+    input = file.readlines()
 
-print(input)
+test_input = '''???.### 1,1,3
+.??..??...?##. 1,1,3
+?#?#?#?#?#?#?#? 1,3,1,6
+????.#...#... 4,1,1
+????.######..#####. 1,6,5
+?###???????? 3,2,1''' 
+test_input = test_input.split('\n')
+#input = test_input
+
+# Initialize the total number of arrangements
+total_arrangements = 0
+# Dictionary for memoization
+memo = {}
+
+def count_arrangements(springs:str, blocks:list, spring_index:int, block_index:int, current_block_length:int) -> int:
+    """
+    This function calculates the number of valid arrangements of springs and blocks.
+
+    Parameters:
+    springs (str): A string of characters, each of which is either '.', '#' or '?'.
+    blocks (list): A list of integers representing the blocks.
+    spring_index (int): The current index in `springs`.
+    block_index (int): The current index in `blocks`.
+    current_block_length (int): The current number of consecutive '#' characters.
+
+    Returns:
+    int: The number of valid arrangements for the current state.
+
+    """
+    # Create a key for the current state
+    state_key = (spring_index, block_index, current_block_length)
+
+    # If the result for the current state is already computed, return it
+    if state_key in memo:
+        return memo[state_key]
+
+    # If all springs are processed
+    if spring_index == len(springs):
+        # If all blocks are used and there's no current block, or the last block is of correct size
+        if (block_index == len(blocks) and current_block_length == 0) or \
+           (block_index == len(blocks) - 1 and blocks[block_index] == current_block_length):
+            return 1
+        else:
+            return 0
+
+    # Initialize the number of arrangements for the current state
+    arrangements = 0
+
+    # Try both possibilities for the current spring ('.' or '#')
+    for spring in ['.', '#']:
+        # If the current spring can be the current possibility
+        if springs[spring_index] == spring or springs[spring_index] == '?':
+            # If the current spring is '.' and there's no current block
+            if spring == '.' and current_block_length == 0:
+                arrangements += count_arrangements(springs, blocks, spring_index + 1, block_index, 0)
+            # If the current spring is '.' and the current block is of correct size
+            elif spring == '.' and current_block_length > 0 and block_index < len(blocks) and blocks[block_index] == current_block_length:
+                arrangements += count_arrangements(springs, blocks, spring_index + 1, block_index + 1, 0)
+            # If the current spring is '#'
+            elif spring == '#':
+                arrangements += count_arrangements(springs, blocks, spring_index + 1, block_index, current_block_length + 1)
+
+    # Store the result for the current state in the memoization dictionary
+    memo[state_key] = arrangements
+
+    # Return the number of arrangements for the current state
+    return arrangements
+
+# Process each line in the input
+for line in input:
+    # Split the line into springs and blocks
+    springs, blocks_string = line.split()
+    # add in 5 copies of the spring separated by a '?'
+    springs = '?'.join([springs,springs,springs,springs,springs])
+    # add in 5 copies of the block_string separated by a ','
+    blocks_string = ','.join([blocks_string,blocks_string,blocks_string,blocks_string,blocks_string])
+    # Convert the blocks string into a list of integers
+    blocks = [int(x) for x in blocks_string.split(',')]
+    # Clear the memoization dictionary
+    memo.clear()
+    # Calculate the number of arrangements for the current line
+    line_arrangements = count_arrangements(springs, blocks, 0, 0, 0)
+    # Add the number of arrangements for the current line to the total number of arrangements
+    total_arrangements += line_arrangements
+
+# Print the total number of arrangements
+print(total_arrangements)