Solve 2022 Day 5 in python

2022/Day5/python/solve.py

@@ -0,0 +1,99 @@
+import os
+import re
+
+def parse_stacks(lines):
+    stacks = {}
+    for line in reversed(lines):
+        regex = re.compile('(?:\[(.)\] ?|    ?)', re.DOTALL)
+        crates = regex.findall(line)
+        for i, crate in enumerate(crates):
+            if stacks.get(i + 1) == None:
+                stacks[i + 1] = []
+            if crate != '':
+                stacks[i + 1].append(crate)
+    return stacks
+
+def part1(lines):
+    crate_definition_lines = []
+    instructions = []
+    for line in lines:
+        if line == "\n":
+            continue
+
+        if line.startswith('move'):
+            regex = re.compile('move (\d+) from (\d+) to (\d+)')
+            matches = regex.match(line).groups()
+            instruction = {
+                'count': int(matches[0]),
+                'from': int(matches[1]),
+                'to': int(matches[2])
+            }
+            instructions.append(instruction)
+        else:
+            crate_definition_lines.append(line)
+
+    # We don't care about the labels
+    crate_definition_lines.pop()
+    stacks = parse_stacks(crate_definition_lines)
+
+    for instruction in instructions:
+        for count in range(instruction['count']):
+            item = stacks[instruction['from']].pop()
+            stacks[instruction['to']].append(item)
+
+    top_crates = []
+
+    for i in stacks:
+        stack = stacks[i]
+        top_crates.append(stack[len(stack) - 1])
+    
+    return ''.join(top_crates)
+
+
+def part2(lines):
+    crate_definition_lines = []
+    instructions = []
+    for line in lines:
+        if line == "\n":
+            continue
+
+        if line.startswith('move'):
+            regex = re.compile('move (\d+) from (\d+) to (\d+)')
+            matches = regex.match(line).groups()
+            instruction = {
+                'count': int(matches[0]),
+                'from': int(matches[1]),
+                'to': int(matches[2])
+            }
+            instructions.append(instruction)
+        else:
+            crate_definition_lines.append(line)
+
+    # We don't care about the labels
+    crate_definition_lines.pop()
+    stacks = parse_stacks(crate_definition_lines)
+
+    for instruction in instructions:
+        temp = []
+        for count in range(instruction['count']):
+            temp.append(stacks[instruction['from']].pop())
+
+        temp.reverse()
+        stacks[int(instruction['to'])] += temp
+
+    top_crates = []
+
+    for i in stacks:
+        stack = stacks[i]
+        top_crates.append(stack[len(stack) - 1])
+    
+    return ''.join(top_crates)
+
+
+dirname = os.path.dirname(__file__)
+filename = os.path.join(dirname, '../input.txt')
+with open(filename) as f:
+    lines = f.readlines()
+
+print(part1(lines))
+print(part2(lines))