From 3fe94bbb0201c4372b074aec853f72f4dcd83140 Mon Sep 17 00:00:00 2001
From: Gabriel Augendre <gabriel@augendre.info>
Date: Tue, 15 Dec 2020 09:22:49 +0100
Subject: [PATCH] Solve day 15 (part 2 bruteforce)

---
 2020/day15_memory.py    | 70 +++++++++++++++++++++++++++++++++++++++++
 2020/inputs/day15       |  1 +
 2020/inputs/day15-test1 |  1 +
 2020/inputs/day15-test2 |  1 +
 2020/inputs/day15-test6 |  1 +
 2020/inputs/day15-test7 |  1 +
 2020/template.py        | 34 ++++++++++++++++++++
 7 files changed, 109 insertions(+)
 create mode 100644 2020/day15_memory.py
 create mode 100644 2020/inputs/day15
 create mode 100644 2020/inputs/day15-test1
 create mode 100644 2020/inputs/day15-test2
 create mode 100644 2020/inputs/day15-test6
 create mode 100644 2020/inputs/day15-test7
 create mode 100644 2020/template.py

diff --git a/2020/day15_memory.py b/2020/day15_memory.py
new file mode 100644
index 0000000..c1a3cf0
--- /dev/null
+++ b/2020/day15_memory.py
@@ -0,0 +1,70 @@
+import functools
+import re
+from typing import Dict, Iterable, List, Tuple, Union
+
+
+def main(filename: str, expected_part_1: int = None, expected_part_2: int = None):
+    print(f"\n+ Running on {filename}")
+    with open(filename) as f:
+        starting_numbers = list(map(int, f.read().strip().split("\n")[0].split(",")))
+
+    counter_part_1 = solve_part_1(starting_numbers)
+
+    print(f"1. Found {counter_part_1}")
+    if expected_part_1:
+        assert expected_part_1 == counter_part_1
+
+    counter_part_2 = solve_part_2(starting_numbers)
+    print(f"2. Found {counter_part_2}")
+    if expected_part_2:
+        assert expected_part_2 == counter_part_2
+
+
+SeenTuple = Union[Tuple[int], Tuple[int, int]]
+Seen = Dict[int, SeenTuple]
+
+
+def solve_part_1(starting_numbers):
+    return solve(starting_numbers, 2020)
+
+
+def solve(starting_numbers, limit):
+    seen = dict()  # type: Seen
+    previous = 0
+    for turn, current in enumerate(starting_numbers):
+        seen[current] = (turn,)
+        previous = current
+    previous_first_time = True
+    for turn in range(len(starting_numbers), limit):
+        if previous_first_time:
+            current = 0
+        else:
+            current = seen[previous][0] - seen[previous][1]
+        seen[current] = seen_tuple(seen, current, turn)
+        previous = current
+        previous_first_time = first_time_seen(seen, previous)
+    return previous
+
+
+def first_time_seen(seen: Seen, previous: int) -> bool:
+    return len(seen[previous]) == 1
+
+
+def seen_tuple(seen: Seen, current: int, turn: int) -> SeenTuple:
+    try:
+        existing = seen[current]
+        return turn, existing[0]
+    except KeyError:
+        return (turn,)
+
+
+def solve_part_2(starting_numbers):
+    return solve(starting_numbers, 30_000_000)
+
+
+if __name__ == "__main__":
+    main("inputs/day15-test1", 436, 175594)
+    main("inputs/day15-test2", 1, 2578)
+    main("inputs/day15-test6", 438, 18)
+    main("inputs/day15-test7", 1836, 362)
+    main("inputs/day15", 595, 1708310)
diff --git a/2020/inputs/day15 b/2020/inputs/day15
new file mode 100644
index 0000000..87eb7a7
--- /dev/null
+++ b/2020/inputs/day15
@@ -0,0 +1 @@
+1,17,0,10,18,11,6
\ No newline at end of file
diff --git a/2020/inputs/day15-test1 b/2020/inputs/day15-test1
new file mode 100644
index 0000000..d743421
--- /dev/null
+++ b/2020/inputs/day15-test1
@@ -0,0 +1 @@
+0,3,6
\ No newline at end of file
diff --git a/2020/inputs/day15-test2 b/2020/inputs/day15-test2
new file mode 100644
index 0000000..55526f5
--- /dev/null
+++ b/2020/inputs/day15-test2
@@ -0,0 +1 @@
+1,3,2
\ No newline at end of file
diff --git a/2020/inputs/day15-test6 b/2020/inputs/day15-test6
new file mode 100644
index 0000000..37bfbbd
--- /dev/null
+++ b/2020/inputs/day15-test6
@@ -0,0 +1 @@
+3,2,1
\ No newline at end of file
diff --git a/2020/inputs/day15-test7 b/2020/inputs/day15-test7
new file mode 100644
index 0000000..4d83fd9
--- /dev/null
+++ b/2020/inputs/day15-test7
@@ -0,0 +1 @@
+3,1,2
\ No newline at end of file
diff --git a/2020/template.py b/2020/template.py
new file mode 100644
index 0000000..7ca2c9c
--- /dev/null
+++ b/2020/template.py
@@ -0,0 +1,34 @@
+import functools
+import re
+from typing import Dict, Iterable, List, Union
+
+
+def main(filename: str, expected_part_1: int = None, expected_part_2: int = None):
+    print(f"\n+ Running on {filename}")
+    with open(filename) as f:
+        data = f.read().strip().split("\n")
+
+    counter_part_1 = solve_part_1(data)
+
+    print(f"1. Found {counter_part_1}")
+    if expected_part_1:
+        assert expected_part_1 == counter_part_1
+
+    counter_part_2 = solve_part_2(data)
+    print(f"2. Found {counter_part_2}")
+    if expected_part_2:
+        assert expected_part_2 == counter_part_2
+
+
+def solve_part_1(data):
+    return 0
+
+
+def solve_part_2(data):
+    return 0
+
+
+if __name__ == "__main__":
+    main("inputs/day14-test1", 436)
+    main("inputs/day14-test2", 1)
+    main("inputs/day14")