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Task/Rep-string/Racket/rep-string.rkt

@@ -0,0 +1,26 @@
+#lang racket
+
+(define (rep-string str)
+  (define len (string-length str))
+  (for/or ([n (in-range 1 len)])
+    (and (let loop ([from n])
+           (or (>= from len)
+               (let ([m (min (- len from) n)])
+                 (and (equal? (substring str from (+ from m))
+                              (substring str 0 m))
+                      (loop (+ n from))))))
+         (<= n (quotient len 2))
+         (substring str 0 n))))
+
+(for ([str '("1001110011"
+             "1110111011"
+             "0010010010"
+             "1010101010"
+             "1111111111"
+             "0100101101"
+             "0100100"
+             "101"
+             "11"
+             "00"
+             "1")])
+  (printf "~a => ~a\n" str (or (rep-string str) "not a rep-string")))