Data commit

Task/Greatest-subsequential-sum/Common-Lisp/greatest-subsequential-sum-1.lisp

@@ -0,0 +1,19 @@
+(defun max-subseq (list)
+  (let ((best-sum 0) (current-sum 0) (end 0))
+    ;; determine the best sum, and the end of the max subsequence
+    (do ((list list (rest list))
+         (i 0 (1+ i)))
+        ((endp list))
+      (setf current-sum (max 0 (+ current-sum (first list))))
+      (when (> current-sum best-sum)
+        (setf end i
+              best-sum current-sum)))
+    ;; take the subsequence of list ending at end, and remove elements
+    ;; from the beginning until the subsequence sums to best-sum.
+    (let* ((sublist (subseq list 0 (1+ end)))
+           (sum (reduce #'+ sublist)))
+      (do ((start 0 (1+ start))
+           (sublist sublist (rest sublist))
+           (sum sum (- sum (first sublist))))
+          ((or (endp sublist) (eql sum best-sum))
+           (values best-sum sublist start (1+ end)))))))

Task/Greatest-subsequential-sum/Common-Lisp/greatest-subsequential-sum-2.lisp

@@ -0,0 +1,7 @@
+(defun max-subseq (seq)
+  (loop for subsequence in (mapcon (lambda (x) (maplist #'reverse (reverse x))) seq)
+        for sum = (reduce #'+ subsequence :initial-value 0)
+        with max-subsequence
+        maximizing sum into max
+        if (= sum max) do (setf max-subsequence subsequence)
+        finally (return max-subsequence))))