Data commit

Task/Topswops/PL-I/topswops.pli

@@ -0,0 +1,32 @@
+(subscriptrange):
+topswap: procedure options (main); /* 12 November 2013 */
+   declare cards(*) fixed (2) controlled, t fixed (2);
+   declare dealt(*) bit(1) controlled;
+   declare (count, i, m, n, c1, c2) fixed binary;
+   declare random builtin;
+
+   do n = 1 to 10;
+      allocate cards(n), dealt(n);
+      /* Take the n cards, in order ... */
+      do i = 1 to n; cards(i) = i; end;
+      /* ... and shuffle them. */
+      do i = 1 to n;
+         c1 = random*n+1; c2 = random*n+1;
+         t = cards(c1); cards(c1) = cards(c2); cards(c2) = t;
+      end;
+      /* If '1' is the first card, game is trivial; swap it with another. */
+      if cards(1) = 1 & n > 1 then
+         do; t = cards(1); cards(1) = cards(2); cards(2) = t; end;
+
+      count = 0;
+      do until (cards(1) = 1);
+         /* take the value of the first card, M, and reverse the first M cards. */
+         m = cards(1);
+         do i = 1 to m/2;
+            t = cards(i); cards(i) = cards(m-i+1); cards(m-i+1) = t;
+         end;
+         count = count + 1;
+      end;
+      put skip edit (n, ':', count) (f(2), a, f(4));
+   end;
+end topswap;