2023 Dec 18th

Python/2023/18/main.py

@@ -0,0 +1,56 @@
+input = open("input", 'r')
+
+
+d = [((p:= line.split(" "))[0], int(p[1]), p[2][2:-2])
+     for line in input]
+
+def drToC(dr):
+    match dr:
+        case "U" | "3":
+            return 1
+        case "D" | "1":
+            return -1
+        case "R" | "0":
+            return 1j
+        case "L" | "2":
+            return -1j
+    return 0
+
+def fill(pos,s):
+    q = {pos}
+    while q:
+        c = q.pop()
+        if c in s: continue
+        s.add(c)
+        for dr in {1,-1,1j,-1j}:
+            q.add(c+dr)
+
+def run():
+    cr = 0
+    s = {0}
+    for dr,ln,_ in d:
+        drC = drToC(dr)
+        for _ in range(ln):
+            cr = cr + drC
+            s.add(cr)
+    fill(-1+1j,s)
+    return len(s)
+
+def run2():
+    v = [0]
+    cr = 0
+    prev = 0
+    area = 1
+
+    for _,_,color in d:
+        ln,dr = int(color[:-1],16), drToC(color[-1])
+        area += ln
+        prev += dr * ln
+        v.append(prev)
+
+    for v1,v2 in zip(v,(v[1:] + [v[0]])):
+        area += (v1.real * v2.imag) - (v1.imag * v2.real)
+    return int(area // 2)
+
+print(run())
+print(run2())