Initial data commit

Task/Burrows-Wheeler-transform/TXR/burrows-wheeler-transform.txr

@@ -0,0 +1,14 @@
+(defvarl eof "\xDC00")
+
+(defun bwt (str)
+  (if (contains eof str)
+    (error "~s: input may not contain ~a" %fun% eof))
+  (let ((seof `@str@eof`))
+    (flow 0..(len seof) (mapcar (op rot seof)) sort (mappend last))))
+
+(defun ibwt (str)
+  (let* ((ch (tuples 1 str))
+         (row (sort ch)))
+    (dotimes (i (pred (len str)))
+      (upd row (mapcar append ch) nsort))
+    [(find-if (op ends-with eof) row) 0..-1]))