Solution to problem 2 in Python

src/Year_2016/P2.py

@@ -45,7 +45,7 @@
 # Your puzzle input is the instructions from the document you found at the
 # front desk. What is the bathroom code?
 
-from typing import Optional, Tuple
+from typing import Optional, Tuple, Union
 
 with open("files/P2.txt") as f:
     instructions = [line for line in f.read().strip().split()]
@@ -117,5 +117,132 @@ def part_1() -> None:
     print(f"The secret code is {secret_code}")
 
 
+# --- Part Two ---
+
+# You finally arrive at the bathroom (it's a several minute walk from the lobby
+# so visitors can behold the many fancy conference rooms and water coolers on
+# this floor) and go to punch in the code. Much to your bladder's dismay, the
+# keypad is not at all like you imagined it. Instead, you are confronted with
+# the result of hundreds of man-hours of bathroom-keypad-design meetings:
+
+#     1
+#   2 3 4
+# 5 6 7 8 9
+#   A B C
+#     D
+
+# You still start at "5" and stop when you're at an edge, but given the same
+# instructions as above, the outcome is very different:
+
+#     You start at "5" and don't move at all (up and left are both edges),
+# ending at 5.
+#     Continuing from "5", you move right twice and down three times (through
+# "6", "7", "B", "D", "D"), ending at D.
+#     Then, from "D", you move five more times (through "D", "B", "C", "C",
+# "B"), ending at B.
+#     Finally, after five more moves, you end at 3.
+
+# So, given the actual keypad layout, the code would be 5DB3.
+
+# Using the same instructions in your puzzle input, what is the correct
+# bathroom code?
+
+
+def move_right_(position: Union[int, str]) -> Union[int, str]:
+    num_dict: dict[Union[int, str], Union[int, str]] = {
+        1: 1,
+        2: 3,
+        3: 4,
+        4: 4,
+        5: 6,
+        6: 7,
+        7: 8,
+        8: 9,
+        9: 9,
+        "A": "B",
+        "B": "C",
+        "C": "C",
+        "D": "D",
+    }
+    return num_dict[position]
+
+
+def move_down_(position: Union[int, str]) -> Union[int, str]:
+    num_dict: dict[Union[int, str], Union[int, str]] = {
+        1: 3,
+        2: 6,
+        3: 7,
+        4: 8,
+        5: 5,
+        6: "A",
+        7: "B",
+        8: "C",
+        9: 9,
+        "A": "A",
+        "B": "D",
+        "C": "C",
+        "D": "D",
+    }
+    return num_dict[position]
+
+
+def move_left_(position: Union[int, str]) -> Union[int, str]:
+    num_dict: dict[Union[int, str], Union[int, str]] = {
+        1: 1,
+        2: 2,
+        3: 2,
+        4: 3,
+        5: 5,
+        6: 5,
+        7: 6,
+        8: 7,
+        9: 8,
+        "A": "A",
+        "B": "A",
+        "C": "B",
+        "D": "D",
+    }
+    return num_dict[position]
+
+
+def move_up_(position: Union[int, str]) -> Union[int, str]:
+    num_dict: dict[Union[int, str], Union[int, str]] = {
+        1: 1,
+        2: 2,
+        3: 1,
+        4: 4,
+        5: 5,
+        6: 2,
+        7: 3,
+        8: 4,
+        9: 9,
+        "A": 6,
+        "B": 7,
+        "C": 8,
+        "D": "B",
+    }
+    return num_dict[position]
+
+
+def part_2() -> None:
+    secret = []
+    for instruction in instructions:
+        pos: Union[int, str] = 5
+        for button in instruction:
+            if button == "D":
+                pos = move_down_(pos)
+            elif button == "U":
+                pos = move_up_(pos)
+            elif button == "R":
+                pos = move_right_(pos)
+            elif button == "L":
+                pos = move_left_(pos)
+        secret.append(pos)
+
+    secret_code = "".join(map(str, (char for char in secret)))
+    print(f"The bathroom code is {secret_code}")
+
+
 if __name__ == "__main__":
     part_1()
+    part_2()