[py] Port 2015_03

py/aoc/__init__.py

@@ -2,7 +2,7 @@ import sys
 import argparse
 from pathlib import Path
 
-from .y2015 import d01, d02
+from .y2015 import d01, d02, d03
 from .y2016 import d01, d02, d03, d04, d05
 from .y2017 import d01, d02, d03, d04, d05, d06, d07, d08, d09
 from .y2018 import d01, d02, d03, d04, d05, d06, d07, d08, d09, d10, d11
@@ -13,6 +13,7 @@ from .y2022 import d01, d02, d03, d04, d05, d06
 DAYS = {
     "2015_01": y2015.d01.solve,
     "2015_02": y2015.d02.solve,
+    "2015_03": y2015.d03.solve,
     "2016_01": y2016.d01.solve,
     "2016_02": y2016.d02.solve,
     "2016_03": y2016.d03.solve,

py/aoc/y2015/d03.py

@@ -0,0 +1,46 @@
+# PART 1
+
+
+def find_doubles(steps):
+    x, y = 0, 0
+    houses = {(0, 0)}
+    for step in steps:
+        if step == "^":
+            y += 1
+        elif step == "v":
+            y -= 1
+        elif step == "<":
+            x -= 1
+        elif step == ">":
+            x += 1
+        houses.add((x, y))
+    return houses
+
+
+# PART 2
+
+
+def split_string(s):
+    s1 = ""
+    s2 = ""
+    while True:
+        if not s:
+            break
+        s1 += s[0]
+        s = s[1:]
+        if not s:
+            break
+        s2 += s[0]
+        s = s[1:]
+    return s1, s2
+
+
+def solve(inputstr):
+    steps = inputstr.strip()
+    doubles = len(find_doubles(steps))
+    print(f"Part 1: {doubles}")
+    santa, robot = split_string(steps)
+    santa_doubles = find_doubles(santa)
+    robot_doubles = find_doubles(robot)
+    doubles_2 = len(santa_doubles | robot_doubles)
+    print(f"Part 2: {doubles_2}")