Finally solve 2019 day 12 and others

2019/d12.py

@@ -1,4 +1,5 @@
 from lib import get_data, str_to_ints
+from math import lcm
 
 
 def freeze(coords, velos):
@@ -40,7 +41,40 @@ def part_1(data):
 
 
 def part_2(data):
-    raise Exception("TBD")
+    steps = []
+    for i in range(3):
+        coords = []
+        velos = []
+
+        for line in data.splitlines():
+            coords.append(str_to_ints(line)[i])
+            velos.append(0)
+
+        seen = {}
+        for step in range(1_000_000):
+            state = tuple(coords) + tuple(velos)
+            if state in seen:
+                steps.append(step)
+                break
+            else:
+                seen[state] = step
+
+            for i in range(len(coords)):
+                for j in range(i + 1, len(coords)):
+                    if coords[i] > coords[j]:
+                        velos[i] -= 1
+                        velos[j] += 1
+                    elif coords[i] < coords[j]:
+                        velos[i] += 1
+                        velos[j] -= 1
+
+            # update coords
+            for i in range(len(coords)):
+                coords[i] += velos[i]
+
+    # Intuition: Find when position repeats on each axis and then find lowest
+    # common multiple for all three values.
+    print(lcm(*steps))
 
 
 def main():

2020/d10.py

@@ -0,0 +1,57 @@
+from lib import get_data
+from collections import defaultdict
+from functools import lru_cache
+
+
+@lru_cache
+def count(xs, current, target):
+    delta_target = target - current
+    if len(xs) == 0:
+        if delta_target <= 3:
+            return 1
+        else:
+            return 0
+
+    x = xs[0]
+    xs = xs[1:]
+
+    total = 0
+    delta = x - current
+
+    if delta > 3:
+        return 0
+
+    if delta <= 3:
+        total += count(xs, x, target)
+
+    total += count(xs, current, target)
+    return total
+
+
+def part_1(data):
+    xs = list(map(int, data.strip().splitlines()))
+    out = max(xs) + 3
+    ds = defaultdict(int)
+
+    c = 0
+    for x in sorted(xs):
+        d = x - c
+        ds[d] += 1
+        c = x
+    d = out - c
+    ds[d] += 1
+
+    a, b = list(ds.values())
+    print(a * b)
+
+    xs = tuple(sorted(xs))
+    print(count(xs, 0, out))
+
+
+def main():
+    data = get_data(__file__)
+    part_1(data)
+
+
+if __name__ == "__main__":
+    main()

2020/d11.py

@@ -0,0 +1,89 @@
+from lib import get_data, Grid2D, add2
+
+data = """L.LL.LL.LL
+LLLLLLL.LL
+L.L.L..L..
+LLLL.LL.LL
+L.LL.LL.LL
+L.LLLLL.LL
+..L.L.....
+LLLLLLLLLL
+L.LLLLLL.L
+L.LLLLL.LL"""
+
+
+def part_1(data):
+    g = Grid2D(data)
+    seen = set()
+    while True:
+        h = g.hash()
+        if h in seen:
+            break
+        seen.add(h)
+
+        ng = g.clone_with_val(".")
+        for r in range(g.n_rows):
+            for c in range(g.n_cols):
+                p = (r, c)
+                s = g[p]
+                if s == ".":
+                    continue
+                occupied = sum([1 if g[nb] == "#" else 0 for nb in g.neighbors_adj(p)])
+                if s == "L" and occupied == 0:
+                    ng[p] = "#"
+                elif s == "#" and occupied >= 4:
+                    ng[p] = "L"
+                else:
+                    ng[p] = s
+        g = ng
+    print(len(g.find("#")))
+
+
+def part_2(data):
+    g = Grid2D(data)
+    seen = set()
+    while True:
+        h = g.hash()
+        if h in seen:
+            break
+        seen.add(h)
+
+        ng = g.clone_with_val(".")
+        for r in range(g.n_rows):
+            for c in range(g.n_cols):
+                p = (r, c)
+                s = g[p]
+                if s == ".":
+                    continue
+
+                occupied = 0
+                for dir in g.COORDS_ORTH + g.COORDS_DIAG:
+                    np = p
+                    while True:
+                        np = add2(np, dir)
+                        if not g.contains(np):
+                            break
+                        elif g[np] == "#":
+                            occupied += 1
+                            break
+                        elif g[np] == "L":
+                            break
+
+                if s == "L" and occupied == 0:
+                    ng[p] = "#"
+                elif s == "#" and occupied >= 5:
+                    ng[p] = "L"
+                else:
+                    ng[p] = s
+        g = ng
+    print(len(g.find("#")))
+
+
+def main():
+    data = get_data(__file__)
+    part_1(data)
+    part_2(data)
+
+
+if __name__ == "__main__":
+    main()

README.md

@@ -123,7 +123,7 @@ Solutions and utility script for Advent of Code challenges in Python.
 - Day 9: 115:00 (Try to read next time.)
 - Day 10: 76:00 (This wasn't easy for me. Fun, though.)
 - Day 11: 21:04 (Too slow, but fun.)
-- Day 12:
+- Day 12: days  (Took me a while to get the right idea.)
 - Day 13: >120:00 (Just struggling so much for some reason.)
 - Day 14: >120:00 (Hmm, wasn't that hard either.)
 - Day 15: >120:00 (I am really weak at the moment.)
@@ -135,16 +135,18 @@ Solutions and utility script for Advent of Code challenges in Python.
 
 ## AoC 2020
 
-- Day 1: 2:48  (people weren't able to submit because of a website outage)
-- Day 2: 4:47  (no leaderboard, you can tell it's getting faster)
-- Day 3: 7:06  (way too slow, lol; time to take it seriously)
-- Day 4: 14:30 (yo, I am just too slow)
-- Day 5: 11:53 (not competitive)
-- Day 6: 4:11  (75th, finally on the leaderboard)
-- Day 7: 24:39 (bad)
-- Day 8: 6:26  (43th, tied George Hotz :)
-- Day 9: 7:37  (choked bad)
-- Day 10:
+- Day 1: 2:48   (people weren't able to submit because of a website outage)
+- Day 2: 4:47   (no leaderboard, you can tell it's getting faster)
+- Day 3: 7:06   (way too slow, lol; time to take it seriously)
+- Day 4: 14:30  (yo, I am just too slow)
+- Day 5: 11:53  (not competitive)
+- Day 6: 4:11   (75th, finally on the leaderboard)
+- Day 7: 24:39  (bad)
+- Day 8: 6:26   (43th, tied George Hotz :)
+- Day 9: 7:37   (choked bad)
+- Day 10: 34:27 (so weak)
+- Day 11: 21:05 (hmmm, I rally have to analyze why I am so slow)
+- Day 12:
 
 
 ## AoC 2022