# HG changeset patch
# User Jordi Gutiérrez Hermoso <jordigh@octave.org>
# Date 1513633367 18000
# Node ID 4e7e7835f1dbcbb7a4589a61ec7309168d35ae10
# Parent  f1f0220b5f7ccef9529a3a75a83fd06520fd1409
day 17

diff --git a/2017/day17.d b/2017/day17.d
new file mode 100644
--- /dev/null
+++ b/2017/day17.d
@@ -0,0 +1,31 @@
+import std.stdio;
+import std.algorithm: find;
+import std.conv: to;
+
+auto getBuffer(ulong skip) {
+  ulong[] circ = [0];
+  ulong pos = 0;
+  foreach(y; 1..2018) {
+    pos = (pos + skip) % circ.length + 1;
+    circ = circ[0..pos] ~ y ~ circ[pos..$];
+  }
+  return circ;
+}
+
+auto getPastZero(ulong skip) {
+  ulong pos = 0;
+  ulong pastzero = 0;
+  foreach(length; 1..50_000_000) {
+    pos = (pos + skip) % length + 1;
+    if (pos == 1) {
+      pastzero = length;
+    }
+  }
+  return pastzero;
+}
+
+void main(string[] args) {
+  auto circ = getBuffer(args[1].to!ulong);
+  writeln(find(circ, 2017)[1]);
+  writeln(getPastZero(args[1].to!ulong));
+}