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Task/Rep-string/REXX/rep-string-1.rexx

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+/* REXX ***************************************************************
+* 11.05.2013 Walter Pachl
+* 14.05.2013 Walter Pachl extend to show additional rep-strings
+**********************************************************************/
+Call repstring '1001110011'
+Call repstring '1110111011'
+Call repstring '0010010010'
+Call repstring '1010101010'
+Call repstring '1111111111'
+Call repstring '0100101101'
+Call repstring '0100100'
+Call repstring '101'
+Call repstring '11'
+Call repstring '00'
+Call repstring '1'
+Exit
+
+repstring:
+Parse Arg s
+sq=''''s''''
+n=length(s)
+Do l=length(s)%2 to 1 By -1
+  If substr(s,l+1,l)=left(s,l) Then Leave
+  End
+If l>0 Then Do
+  rep_str=left(s,l)
+  Do i=1 By 1
+    If substr(s,i*l+1,l)<>rep_str Then
+      Leave
+    End
+  If left(copies(rep_str,n),length(s))=s Then Do
+    Call show_rep rep_str              /* show result                */
+    Do i=length(rep_str)-1 To 1 By -1  /* look for shorter rep_str-s */
+      rep_str=left(s,i)
+      If left(copies(rep_str,n),length(s))=s Then
+        Call show_rep rep_str
+      End
+    End
+  Else
+    Call show_norep
+  End
+Else
+  Call show_norep
+Return
+
+show_rep:
+  Parse Arg rs
+  Say right(sq,12) 'has a repetition length of' length(rs) 'i.e.' ''''rs''''
+  Return
+show_norep:
+  Say right(sq,12) 'is not a repeated string'
+  Return