Create day15.py

2020/Python/day15.py

@@ -0,0 +1,46 @@
+def parse_data() -> list[int]:
+    numbers = []
+    with open("input.txt") as file:
+        for line in file:
+            numbers += map(int, line.split(","))
+    return numbers
+
+
+def solve_p1(data: list[int]) -> int:
+    turns = {}
+    curr_turn = 1
+    last_num = 0
+
+    def shift(_number, _turn) -> None:
+        if _number in turns:
+            (_turn_before, _turn_last) = turns[_number]
+            turns[_number] = (_turn_last, _turn)
+        else:
+            turns[_number] = (-1, _turn)
+
+    for number in data:
+        turns[number] = (-1, curr_turn)
+        last_num = number
+        curr_turn += 1
+
+    for i in range(curr_turn, 2021):
+        if last_num in turns:
+            (before, last) = turns[last_num]
+            if before != -1:
+                age = last - before
+                last_num = age
+                shift(age, i)
+                continue
+        last_num = 0
+        shift(0, i)
+
+    return last_num
+
+
+def solve_p2(data: list[int]) -> int:
+    pass
+
+
+DATA = parse_data()
+print(solve_p1(DATA))
+print(solve_p2(DATA))