Data commit

Task/Non-continuous-subsequences/REXX/non-continuous-subsequences.rexx

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+/*REXX program lists all the  non─continuous subsequences  (NCS),   given a sequence.   */
+parse arg list                                   /*obtain optional argument from the CL.*/
+if list='' | list==","  then list= 1 2 3 4 5     /*Not specified?  Then use the default.*/
+say 'list='  space(list);             say        /*display the list to the terminal.    */
+w= words(list)                                   /*W:  is the number of items in list.  */
+nums= strip( left(123456789, w) )                /*build a string of decimal digits.    */
+tail= right(nums, max(0, w-2) )                  /*construct a fast tail for comparisons*/
+#= 0                                             /*#:  number of non─continuous subseq. */
+      do j=13  to left(nums,1) || tail           /*step through list (using smart start)*/
+      if verify(j, nums) \== 0  then iterate     /*Not one of the chosen  (sequences) ? */
+      f= left(j, 1)                              /*use the fist decimal digit of  J.    */
+      NCS= 0                                     /*so far, no non─continuous subsequence*/
+               do k=2  for length(j)-1           /*search for  "       "          "     */
+               x= substr(j, k, 1)                /*extract a single decimal digit of  J.*/
+               if x  <= f    then iterate j      /*if next digit ≤, then skip this digit*/
+               if x \== f+1  then NCS= 1         /*it's OK as of now  (that is, so far).*/
+               f= x                              /*now have a  new  next decimal digit. */
+               end   /*k*/
+      $=
+      if \NCS  then iterate                      /*not OK?  Then skip this number (item)*/
+      #= # + 1                                   /*Eureka!  We found a number (or item).*/
+               do m=1  for length(j)             /*build a sequence string to display.  */
+               $= $ word(list, substr(j, m, 1) ) /*obtain a number (or item) to display.*/
+               end   /*m*/
+
+      say 'a non─continuous subsequence: '   $   /*show the non─continuous subsequence. */
+      end         /*j*/
+say                                              /*help ensure visual fidelity in output*/
+if #==0  then #= 'no'                            /*make it look more gooder Angleshy.   */
+say  #   "non─continuous subsequence"s(#)    'were found.'             /*handle plurals.*/
+exit 0                                           /*stick a fork in it,  we're all done. */
+/*──────────────────────────────────────────────────────────────────────────────────────*/
+s:  if arg(1)==1  then return '';   return word( arg(2) 's',  1)    /*simple pluralizer.*/