Optimized solution

src/Year_2015/P3.py

@@ -21,41 +21,29 @@
 #     ^v^v^v^v^v delivers a bunch of presents to some very lucky children at
 # only 2 houses.
 
-from typing import Tuple
-
 with open("files/P3.txt") as f:
-    moves = [line for line in f.read().strip().split()][0]
+    moves = [line for line in f.read().strip()]
 
 
-def move_up(pos: Tuple[int, int]) -> Tuple[int, int]:
-    return pos[0], pos[1] + 1
-
-
-def move_down(pos: Tuple[int, int]) -> Tuple[int, int]:
-    return pos[0], pos[1] - 1
-
-
-def move_left(pos: Tuple[int, int]) -> Tuple[int, int]:
-    return pos[0] - 1, pos[1]
-
-
-def move_right(pos: Tuple[int, int]) -> Tuple[int, int]:
-    return pos[0] + 1, pos[1]
+Position = tuple[int, int]
+DIRECTIONS: dict[str, Position] = {
+    "^": (0, 1),
+    "v": (0, -1),
+    "<": (-1, 0),
+    ">": (1, 0),
+}
 
 
 def part_1() -> None:
-    pos = [(0, 0)]
+    x, y = 0, 0
+    visited: set[Position] = {(x, y)}
     for move in moves:
-        if move == "^":
-            pos.append(move_up(pos[-1]))
-        elif move == "v":
-            pos.append(move_down(pos[-1]))
-        elif move == "<":
-            pos.append(move_left(pos[-1]))
-        elif move == ">":
-            pos.append(move_right(pos[-1]))
+        delta_x, delta_y = DIRECTIONS[move]
+        x += delta_x
+        y += delta_y
+        visited.add((x, y))
 
-    print(f"{len(set(pos))} houses receive at least one present")
+    print(f"{len(visited)} houses receive at least one present")
 
 
 # --- Part Two ---
@@ -81,33 +69,23 @@ def part_1() -> None:
 
 
 def part_2():
-    santa = [(0, 0)]
-    robo_santa = [(0, 0)]
-    for idx, move in enumerate(moves):
-        if move == "^":
-            if idx % 2 == 0:
-                santa.append(move_up(santa[-1]))
-            else:
-                robo_santa.append(move_up(robo_santa[-1]))
-        elif move == "v":
-            if idx % 2 == 0:
-                santa.append(move_down(santa[-1]))
-            else:
-                robo_santa.append(move_down(robo_santa[-1]))
-        elif move == "<":
-            if idx % 2 == 0:
-                santa.append(move_left(santa[-1]))
-            else:
-                robo_santa.append(move_left(robo_santa[-1]))
-        elif move == ">":
-            if idx % 2 == 0:
-                santa.append(move_right(santa[-1]))
-            else:
-                robo_santa.append(move_right(robo_santa[-1]))
+    x_santa, y_santa = 0, 0
+    x_robo, y_robo = 0, 0
+    visited: set[Position] = {(0, 0)}
 
-    print(
-        f"{len(set(santa + robo_santa))} houses receive at least one present"
-    )
+    for idx, move in enumerate(moves):
+        delta_x, delta_y = DIRECTIONS[move]
+        # santa's turn
+        if idx % 2:
+            x_santa += delta_x
+            y_santa += delta_y
+            visited.add((x_santa, y_santa))
+        else:
+            x_robo += delta_x
+            y_robo += delta_y
+            visited.add((x_robo, y_robo))
+
+    print(f"{len(visited)} houses receive at least one present")
 
 
 if __name__ == "__main__":