Data commit

Task/Topswops/Nim/topswops.nim

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+import strformat
+
+const maxBest = 32
+var best: array[maxBest, int]
+
+proc trySwaps(deck: seq[int], f, d, n: int) =
+  if d > best[n]:
+    best[n] = d
+
+  for i in countdown(n - 1, 0):
+    if deck[i] == -1 or deck[i] == i:
+      break
+    if d + best[i] <= best[n]:
+      return
+
+  var deck2 = deck
+  for i in 1..<n:
+    var k = 1 shl i
+    if deck2[i] == -1:
+      if (f and k) != 0:
+        continue
+    elif deck2[i] != i:
+      continue
+
+    deck2[0] = i
+    for j in countdown(i - 1, 0):
+      deck2[i - j] = deck[j]
+    trySwaps(deck2, f or k, d + 1, n)
+
+proc topswops(n: int): int =
+  assert(n > 0 and n < maxBest)
+  best[n] = 0
+  var deck0 = newSeq[int](n + 1)
+  for i in 1..<n:
+    deck0[i] = -1
+  trySwaps(deck0, 1, 0, n)
+  best[n]
+
+for i in 1..10:
+  echo &"{i:2}: {topswops(i):2}"