nim :D

.gitignore

@@ -0,0 +1 @@
+/p15

p15.nim

@@ -0,0 +1,33 @@
+import tables
+
+iterator play(start: seq[int]): int =
+  var spoke = initTable[int, int]()
+  var turn = 0
+  var nextSpeak = 0
+
+  for i in start:
+    turn += 1
+    spoke[i] = turn
+    yield i
+    nextSpeak = 0
+
+  while true:
+    turn += 1
+    yield nextSpeak
+    var lastSpoke = spoke.getOrDefault(nextSpeak, -1)
+    spoke[nextSpeak] = turn
+
+    if lastSpoke == -1:
+      nextSpeak = 0
+    else:
+      nextSpeak = turn - lastSpoke
+
+proc solve(s: seq[int], n: int): int =
+  var i = 0
+  for x in play(s):
+    inc i
+    if i == n:
+      echo x
+      break
+
+echo solve(@[5,1,9,18,13,8,0], 30000000)