<100ms ha!

1 files changed, 44 insertions, 0 deletions

diff --git a/2023/18/solve.py b/2023/18/solve.py
new file mode 100644
index 0000000..04bda99
--- /dev/null
+++ b/2023/18/solve.py
@@ -0,0 +1,44 @@
+L = [
+    (s := l.split(" ")) and (s[0], int(s[1]), s[2][2:-2])
+    for l in open("input").readlines()
+]
+
+
+# rosetta, shoelace, day 10
+def area(loop):
+    x, y = zip(*loop)
+    return abs(sum(i * j for i, j in zip(x, y[1:] + y[:1])) - sum(i * j for i, j in zip(x[1:] + x[:1], y))) // 2
+
+
+def part1():
+    mv = {"R": (0, 1), "D": (1, 0), "L": (0, -1), "U": (-1, 0)}
+
+    c = (0, 0)
+    mp = [c]
+    for d, n, _ in L:
+        nc = mv[d]
+        c = (c[0] + nc[0] * n, c[1] + nc[1] * n)
+        mp.append(c)
+
+    s = sum(l[1] for l in L)
+    print(area(mp) + s // 2 + 1)
+
+
+def part2():
+    mv = [(0, 1), (1, 0), (0, -1), (-1, 0)]
+
+    c = (0, 0)
+    mp = [c]
+    s = 0
+    for _, _, h in L:
+        n = int(h[:-1], 16)
+        nc = mv[int(h[-1])]
+        c = (c[0] + nc[0] * n, c[1] + nc[1] * n)
+        s += n
+        mp.append(c)
+
+    print(area(mp) + s // 2 + 1)
+
+
+part1()
+part2()