Start with 2021

2021/d1.py

@@ -0,0 +1,20 @@
+from lib import get_data
+from lib import ints
+
+data = get_data(__file__)
+xs = ints(data)
+
+t = 0
+for a, b in zip(xs, xs[1:]):
+    if b > a:
+        t += 1
+print(t)
+
+t = 0
+prev_sum = 10**12
+for i in range(len(xs) - 2):
+    s = sum(xs[i : i + 3])
+    if s > prev_sum:
+        t += 1
+    prev_sum = s
+print(t)

2021/d2.py

@@ -0,0 +1,24 @@
+from lib import get_data
+from lib import ints
+
+data = get_data(__file__)
+
+aim, h2, d2 = 0, 0, 0
+h, d = 0, 0
+for line in data.splitlines():
+    (v,) = ints(line)
+    if "forward" in line:
+        h2 += v
+        d2 += aim * v
+        h += v
+    elif "down" in line:
+        aim += v
+        d += v
+    elif "up" in line:
+        aim -= v
+        d -= v
+    else:
+        assert False
+
+print(h * d)
+print(h2 * d2)

2021/d3.py

@@ -0,0 +1,56 @@
+from lib import get_data
+from lib import ints
+from collections import defaultdict
+
+data = get_data(__file__)
+
+
+def count_one_zero(xs, index):
+    ones, zeros = 0, 0
+    for x in xs:
+        if x[index] == "1":
+            ones += 1
+        elif x[index] == "0":
+            zeros += 1
+        else:
+            assert False
+    return (ones, zeros)
+
+
+a = ""
+b = ""
+lines = list(data.strip().splitlines())
+for i in range(len(lines[0])):
+    ones, zeros = count_one_zero(lines, i)
+    if ones > zeros:
+        a += "1"
+        b += "0"
+    elif zeros > ones:
+        a += "0"
+        b += "1"
+    else:
+        assert False
+a, b = int(a, 2), int(b, 2)
+print(a * b)
+
+lines = list(data.strip().splitlines())
+for i in range(len(lines[0])):
+    ones, zeros = count_one_zero(lines, i)
+    c = "1" if ones >= zeros else "0"
+    lines = [l for l in lines if l[i] == c]
+    if len(lines) == 1:
+        break
+(line,) = lines
+a = int(line, 2)
+
+lines = list(data.strip().splitlines())
+for i in range(len(lines[0])):
+    ones, zeros = count_one_zero(lines, i)
+    c = "0" if zeros <= ones else "1"
+    lines = [l for l in lines if l[i] == c]
+    if len(lines) == 1:
+        break
+
+(line,) = lines
+b = int(line, 2)
+print(a * b)

2021/lib.py

@@ -0,0 +1 @@
+../lib.py

README.md

@@ -170,6 +170,13 @@ Solutions and utility script for Advent of Code challenges in Python.
 - Day 24: 15:38 (Close to leaderboard)
 - Day 25: 14:40 (Way too slow)
 
+## AoC 2021
+
+- Day 1:  4:01   (Haha. Why am I so bad?!?!)
+- Day 2:  6:36   (Okay. I might as well stop doing these.)
+- Day 3: 23:46   (How long can I take when I try to take long?)
+- Day 4:
+
 ## AoC 2022
 
 Done with this. Overall everything is solvable. It's more about consistency