[py] Port 2018_05

py/aoc/__init__.py

@@ -2,7 +2,7 @@ import sys
 import argparse
 from pathlib import Path
 
-from .y2018 import d01, d02, d03, d04
+from .y2018 import d01, d02, d03, d04, d05
 from .y2020 import d10
 from .y2021 import d14
 from .y2022 import d01, d02, d03, d04, d05, d06
@@ -12,6 +12,7 @@ DAYS = {
     "2018_02": y2018.d02.solve,
     "2018_03": y2018.d03.solve,
     "2018_04": y2018.d04.solve,
+    "2018_05": y2018.d05.solve,
     "2020_10": y2020.d10.solve,
     "2021_14": y2021.d14.solve,
     "2022_01": y2022.d01.solve,

py/aoc/y2018/d05.py

@@ -0,0 +1,79 @@
+# PART 1
+
+
+def naive_react(pol):
+    for i in range(len(pol) - 1):
+        if pol[i].lower() == pol[i + 1].lower() and pol[i] != pol[i + 1]:
+            print("Naive react says: More reacting is possible.")
+
+
+def react(pol):
+    while True:
+        i = 0
+        while i < len(pol) - 1:
+            pol_cur, pol_next = pol[i], pol[i + 1]
+            if pol_cur.lower() == pol_next.lower() and pol_cur != pol_next:
+                del pol[i]
+                del pol[i]
+                i = max(0, i - 1)
+            else:
+                i += 1
+        else:
+            return
+
+
+# def react(pol):
+# 	start = 0
+# 	while True:
+# 		i = start
+# 		while i < len(pol) - 1:
+# 			if pol[i].lower() == pol[i+1].lower() and pol[i] != pol[i+1]:
+# 				del pol[i]
+# 				del pol[i]
+# 				start = max(0, start - 1)
+# 				break
+# 			elif i == start + 1:
+# 				start = i
+# 			i += 1
+# 		else:
+# 			return
+
+
+def result(pol):
+    l = pol.copy()
+    # print("".join(l))
+    react(l)
+    # print("->", "".join(l))
+    naive_react(l)
+    return len(l)
+
+
+# PART 2
+
+
+def removable_chars(pol):
+    return set(c.lower() for c in pol)
+
+
+def remove(pol, char):
+    return [c for c in pol if c.lower() != char.lower()]
+
+
+def find_obstructing(pol):
+    results = []
+    chars = removable_chars(pol)
+    for c in sorted(chars):
+        l = remove(pol, c)
+        n = result(l)
+        # print("Removed", c, "-> length", n)
+        results.append(n)
+    return min(results)
+
+
+def solve(inputstr):
+    pols = [list(line) for line in inputstr.splitlines()]
+    for pol in pols:
+        length = result(pol)
+        print(f"Part 1: {length}")
+        best_result = find_obstructing(pol)
+        print(f"Part 2: {best_result}")