Solve a couple of 2017 problems.

2017/d10.py

@@ -0,0 +1,64 @@
+from lib import str_to_ints
+
+def part_1(data):
+    ns = list(range(256))
+    lenghts = str_to_ints(data)
+    i = 0
+    skip_size = 0
+
+    for length in lenghts:
+        a, b = i, (i + length) % len(ns)
+        if a <= b:
+            ns[a:b] = reversed(ns[a:b])
+        else:
+            rev = list(reversed(ns[a:] + ns[:b]))
+            ns[a:] = rev[:len(ns) - a]
+            ns[:b] = rev[-b:]
+        i = (i + length + skip_size) % len(ns)
+        skip_size += 1
+    print(ns[0] * ns[1])
+
+
+def part_2(data):
+    ns = list(range(256))
+    lenghts = list(map(ord, data)) + [17, 31, 73, 47, 23]
+    rounds = 64
+
+    i = 0
+    skip_size = 0
+    for _ in range(rounds):
+        for length in lenghts:
+            assert length < 256
+            a, b = i, (i + length) % len(ns)
+            if a <= b:
+                ns[a:b] = reversed(ns[a:b])
+            else:
+                rev = list(reversed(ns[a:] + ns[:b]))
+                ns[a:] = rev[:len(ns) - a]
+                if b != 0:
+                    ns[:b] = rev[-b:]
+            i = (i + length + skip_size) % len(ns)
+            assert len(ns) == 256
+            skip_size += 1
+
+    out = ""
+    for i in range(0, len(ns), 16):
+        r = 0
+        for j in range(i, i + 16):
+            r ^= ns[j]
+        out += f"{r:02x}"
+    return out
+
+
+def main():
+    data = open(0).read().strip()
+    part_1(data)
+    assert part_2("") == "a2582a3a0e66e6e86e3812dcb672a272"
+    assert part_2("AoC 2017") == "33efeb34ea91902bb2f59c9920caa6cd"
+    assert part_2("1,2,3") == "3efbe78a8d82f29979031a4aa0b16a9d"
+    assert part_2("1,2,4") =="63960835bcdc130f0b66d7ff4f6a5a8e"
+    print(part_2(data))
+
+
+if __name__ == "__main__":
+    main()