Solution for problem 9 in Python

src/Year_2018/P9.py

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+# --- Day 9: Marble Mania ---
+
+# You talk to the Elves while you wait for your navigation system to
+# initialize. To pass the time, they introduce you to their favorite marble
+# game.
+
+# The Elves play this game by taking turns arranging the marbles in a circle
+# according to very particular rules. The marbles are numbered starting with 0
+# and increasing by 1 until every marble has a number.
+
+# First, the marble numbered 0 is placed in the circle. At this point, while it
+# contains only a single marble, it is still a circle: the marble is both
+# clockwise from itself and counter-clockwise from itself. This marble is
+# designated the current marble.
+
+# Then, each Elf takes a turn placing the lowest-numbered remaining marble into
+# the circle between the marbles that are 1 and 2 marbles clockwise of the
+# current marble. (When the circle is large enough, this means that there is
+# one marble between the marble that was just placed and the current marble.)
+# The marble that was just placed then becomes the current marble.
+
+# However, if the marble that is about to be placed has a number which is a
+# multiple of 23, something entirely different happens. First, the current
+# player keeps the marble they would have placed, adding it to their score. In
+# addition, the marble 7 marbles counter-clockwise from the current marble is
+# removed from the circle and also added to the current player's score. The
+# marble located immediately clockwise of the marble that was removed becomes
+# the new current marble.
+
+# For example, suppose there are 9 players. After the marble with value 0 is
+# placed in the middle, each player (shown in square brackets) takes a turn.
+# The result of each of those turns would produce circles of marbles like this,
+# where clockwise is to the right and the resulting current marble is in
+# parentheses:
+
+# [-] (0)
+# [1]  0 (1)
+# [2]  0 (2) 1
+# [3]  0  2  1 (3)
+# [4]  0 (4) 2  1  3
+# [5]  0  4  2 (5) 1  3
+# [6]  0  4  2  5  1 (6) 3
+# [7]  0  4  2  5  1  6  3 (7)
+# [8]  0 (8) 4  2  5  1  6  3  7
+# [9]  0  8  4 (9) 2  5  1  6  3  7
+# [1]  0  8  4  9  2(10) 5  1  6  3  7
+# [2]  0  8  4  9  2 10  5(11) 1  6  3  7
+# [3]  0  8  4  9  2 10  5 11  1(12) 6  3  7
+# [4]  0  8  4  9  2 10  5 11  1 12  6(13) 3  7
+# [5]  0  8  4  9  2 10  5 11  1 12  6 13  3(14) 7
+# [6]  0  8  4  9  2 10  5 11  1 12  6 13  3 14  7(15)
+# [7]  0(16) 8  4  9  2 10  5 11  1 12  6 13  3 14  7 15
+# [8]  0 16  8(17) 4  9  2 10  5 11  1 12  6 13  3 14  7 15
+# [9]  0 16  8 17  4(18) 9  2 10  5 11  1 12  6 13  3 14  7 15
+# [1]  0 16  8 17  4 18  9(19) 2 10  5 11  1 12  6 13  3 14  7 15
+# [2]  0 16  8 17  4 18  9 19  2(20)10  5 11  1 12  6 13  3 14  7 15
+# [3]  0 16  8 17  4 18  9 19  2 20 10(21) 5 11  1 12  6 13  3 14  7 15
+# [4]  0 16  8 17  4 18  9 19  2 20 10 21  5(22)11  1 12  6 13  3 14  7 15
+# [5]  0 16  8 17  4 18(19) 2 20 10 21  5 22 11  1 12  6 13  3 14  7 15
+# [6]  0 16  8 17  4 18 19  2(24)20 10 21  5 22 11  1 12  6 13  3 14  7 15
+# [7]  0 16  8 17  4 18 19  2 24 20(25)10 21  5 22 11  1 12  6 13  3 14  7 15
+
+# The goal is to be the player with the highest score after the last marble is
+# used up. Assuming the example above ends after the marble numbered 25, the
+# winning score is 23+9=32 (because player 5 kept marble 23 and removed marble
+# 9, while no other player got any points in this very short example game).
+
+# Here are a few more examples:
+
+#     10 players; last marble is worth 1618 points: high score is 8317
+#     13 players; last marble is worth 7999 points: high score is 146373
+#     17 players; last marble is worth 1104 points: high score is 2764
+#     21 players; last marble is worth 6111 points: high score is 54718
+#     30 players; last marble is worth 5807 points: high score is 37305
+
+# What is the winning Elf's score?
+
+from collections import defaultdict, deque
+from typing import Dict
+
+with open("files/P9.txt") as f:
+    play = [line for line in f.read().strip().split()]
+
+players, marbles = int(play[0]), int(play[6])
+
+
+def part_1() -> None:
+    marble, pos = 1, 0
+    circle = deque([0])
+    scores: Dict[int, int] = defaultdict(int)
+
+    while marble < marbles:
+        if marble % 23 != 0:
+            pos += 2
+            circle.rotate(-pos)
+            circle.appendleft(marble)
+        else:
+            scores[player] += marble
+            pos -= 7
+            circle.rotate(-pos)
+            scores[player] += circle.popleft()
+        marble += 1
+        pos = 0
+        player: int = marble % players
+
+    print(f"The winning score is {max(scores.values())}")
+
+
+# --- Part Two ---
+
+# Amused by the speed of your answer, the Elves are curious:
+
+# What would the new winning Elf's score be if the number of the last marble
+# were 100 times larger?
+
+
+def part_2() -> None:
+    marble, pos = 1, 0
+    circle = deque([0])
+    scores: Dict[int, int] = defaultdict(int)
+
+    while marble < marbles * 100:
+        if marble % 23 != 0:
+            pos += 2
+            circle.rotate(-pos)
+            circle.appendleft(marble)
+        else:
+            scores[player] += marble
+            pos -= 7
+            circle.rotate(-pos)
+            scores[player] += circle.popleft()
+        marble += 1
+        pos = 0
+        player: int = marble % players
+
+    print(f"The new winning score is {max(scores.values())}")
+
+
+if __name__ == "__main__":
+    part_1()
+    part_2()