Initial data commit

Task/Sorting-algorithms-Permutation-sort/Common-Lisp/sorting-algorithms-permutation-sort-1.lisp

@@ -0,0 +1,34 @@
+(defun factorial (n)
+  (loop for result = 1 then (* i result)
+        for i from 2 to n
+        finally (return result)))
+
+(defun nth-permutation (k sequence)
+  (if (zerop (length sequence))
+      (coerce () (type-of sequence))
+      (let ((seq (etypecase sequence
+                   (vector (copy-seq sequence))
+                   (sequence (coerce sequence 'vector)))))
+        (loop for j from 2 to (length seq)
+              do (setq k (truncate (/ k (1- j))))
+              do (rotatef (aref seq (mod k j))
+                          (aref seq (1- j)))
+              finally (return (coerce seq (type-of sequence)))))))
+
+(defun sortedp (fn sequence)
+  (etypecase sequence
+    (list (loop for previous = #1='#:foo then i
+                for i in sequence
+                always (or (eq previous #1#)
+                           (funcall fn i previous))))
+    ;; copypasta
+    (vector (loop for previous = #1# then i
+                  for i across sequence
+                  always (or (eq previous #1#)
+                             (funcall fn i previous))))))
+
+(defun permutation-sort (fn sequence)
+  (loop for i below (factorial (length sequence))
+        for permutation = (nth-permutation i sequence)
+        when (sortedp fn permutation)
+          do (return permutation)))

Task/Sorting-algorithms-Permutation-sort/Common-Lisp/sorting-algorithms-permutation-sort-2.lisp

@@ -0,0 +1,10 @@
+CL-USER> (time (permutation-sort #'> '(8 3 10 6 1 9 7 2 5 4)))
+Evaluation took:
+  5.292 seconds of real time
+  5.204325 seconds of total run time (5.176323 user, 0.028002 system)
+  [ Run times consist of 0.160 seconds GC time, and 5.045 seconds non-GC time. ]
+  98.34% CPU
+  12,337,938,025 processor cycles
+  611,094,240 bytes consed
+
+(1 2 3 4 5 6 7 8 9 10)