September 2017 Update

Task/Self-referential-sequence/Zkl/self-referential-sequence.zkl

@@ -0,0 +1,32 @@
+N:=0d1_000_001;
+
+fcn lookAndJustSaying(seed){ // numeric String --> numeric String
+   "9876543210".pump(String,'wrap(n){
+      (s:=seed.inCommon(n)) and String(s.len(),n) or ""
+   });
+}
+fcn sequence(seed){ // numeric string --> sequence until it repeats
+   seq:=L();
+   while(not seq.holds(seed)){ seq.append(seed); seed=lookAndJustSaying(seed); }
+   seq
+}
+fcn decending(str) //--> True if digits are in descending (or equal) order
+   { (not str.walker().zipWith('<,str[1,*]).filter1()) }
+
+szs:=List.createLong(25); max:=0;
+foreach seed in (N){
+   z:=seed.toString();
+   if(decending(z)){ // 321 generates same sequence as 312,132,123,213
+      len:=sequence(z).len();
+      if(len>max) szs.clear();
+      if(len>=max){ szs.append(seed.toString()); max=len; }
+   }
+}
+
+// List permutations of longest seeds
+// ("9900"-->(((9,0,0,9),...))-->((9,0,0,9),...)-->("9009"...)
+//        -->remove numbers w/leading zeros-->remove dups
+zs:=szs.apply(Utils.Helpers.permute).flatten().apply("concat")
+   .filter(fcn(s){ s[0]!="0" }) : Utils.Helpers.listUnique(_);
+println(max," iterations for ",zs.concat(", "));
+zs.pump(Console.println,sequence,T("concat",", "));