20

20/20.py

@@ -0,0 +1,76 @@
+from dataclasses import dataclass
+
+with open('input') as file:
+    xs = [int(x) for x in file.read().strip().split('\n')]
+
+@dataclass
+class Node:
+    p: 'Node'
+    n: 'Node'
+    d: int
+    def __str__(self):
+        return str(self.d)
+    __repr__ = __str__
+    def move(self, i):
+        if i==0:
+            return
+        if i>0:
+            left1 = self.p
+            left2 = self.n
+            left1.n = left2
+            left2.p = left1
+            right1 = self
+            for _ in range(i%(len(xs)-1)):
+                right1 = right1.n
+            right2 = right1.n
+            right1.n = self
+            right2.p = self
+            self.p = right1
+            self.n = right2
+        else:
+            right1 = self.p
+            right2 = self.n
+            right1.n = right2
+            right2.p = right1
+            left2 = self
+            for _ in range((-i)%(len(xs)-1)):
+                left2 = left2.p
+            left1 = left2.p
+            left1.n = self
+            left2.p = self
+            self.p = left1
+            self.n = left2
+
+
+nodes = [Node(None, None, x) for x in xs]
+for l, r in zip(nodes, nodes[1:]):
+    l.n = r
+    r.p = l
+nodes[0].p = nodes[-1]
+nodes[-1].n = nodes[0]
+for x in nodes:
+    x.move(x.d)
+s = 0
+zero = nodes[xs.index(0)]
+for _ in range(3):
+    for _ in range(1000):
+        zero = zero.n
+    s += zero.d
+print(s)
+
+nodes = [Node(None, None, x*811589153) for x in xs]
+for l, r in zip(nodes, nodes[1:]):
+    l.n = r
+    r.p = l
+nodes[0].p = nodes[-1]
+nodes[-1].n = nodes[0]
+for _ in range(10):
+    for x in nodes:
+        x.move(x.d)
+s = 0
+zero = nodes[xs.index(0)]
+for _ in range(3):
+    for _ in range(1000):
+        zero = zero.n
+    s += zero.d
+print(s)