Data commit

Task/Topswops/Julia/topswops.julia

@@ -0,0 +1,65 @@
+function fannkuch(n)
+	n == 1 && return 0
+	n == 2 && return 1
+	p = [1:n]
+	q = copy(p)
+	s = copy(p)
+	sign = 1; maxflips = sum = 0
+	while true
+		q0 = p[1]
+		if q0 != 1
+			for i = 2:n
+				q[i] = p[i]
+			end
+			flips = 1
+			while true
+				qq = q[q0] #??
+				if qq == 1
+					sum += sign*flips
+					flips > maxflips && (maxflips = flips)
+					break
+				end
+				q[q0] = q0
+				if q0 >= 4
+					i = 2; j = q0-1
+					while true
+						t = q[i]
+						q[i] = q[j]
+						q[j] = t
+						i += 1
+						j -= 1
+						i >= j && break
+					end
+				end
+				q0 = qq
+				flips += 1
+			end
+		end
+		#permute
+		if sign == 1
+			t = p[2]
+			p[2] = p[1]
+			p[1] = t
+			sign = -1
+		else
+			t = p[2]
+			p[2] = p[3]
+			p[3] = t
+			sign = 1
+			for i = 3:n
+				sx = s[i]
+				if sx != 1
+					s[i] = sx-1
+					break
+				end
+				i == n && return maxflips
+				s[i] = i
+				t = p[1]
+				for j = 1:i
+					p[j] = p[j+1]
+				end
+				p[i+1] = t
+			end
+		end
+	end
+end