Data commit

Task/Greatest-subsequential-sum/Icon/greatest-subsequential-sum.icon

@@ -0,0 +1,22 @@
+procedure main()
+L1 := [-1,-2,3,5,6,-2,-1,4,-4,2,-1]     # sample list
+L  := [-1,1,2,3,4,-11]|||L1             # prepend a local maximum into the mix
+write(ximage(maxsubseq(L)))
+end
+
+link ximage      # to show lists
+
+procedure maxsubseq(L)                    #: return the subsequence of L with maximum positive sum
+local i,maxglobal,maxglobalI,maxlocal,maxlocalI
+
+maxglobal := maxlocal := 0                                           # global and local maxima
+
+every i := 1 to *L do  {
+   if (maxlocal := max(maxlocal +L[i],0)) > 0 then
+      if /maxlocalI then maxlocalI := [i,i] else maxlocalI[2] := i   # local maxima subscripts
+   else maxlocalI := &null                                           # reset subsequence
+   if maxglobal <:= maxlocal then                                    # global maxima
+      maxglobalI := copy(maxlocalI)
+   }
+return L[(\maxglobalI)[1]:maxglobalI[2]] | []                        # return sub-sequence or empty list
+end