Data update

Task/Burrows-Wheeler-transform/Dart/burrows-wheeler-transform.dart

@@ -0,0 +1,67 @@
+import "dart:io";
+
+void main() {
+  List<String> tests = [
+    "banana",
+    "appellee",
+    "dogwood",
+    "TO BE OR NOT TO BE OR WANT TO BE OR NOT?",
+    "SIX.MIXED.PIXIES.SIFT.SIXTY.PIXIE.DUST.BOXES",
+    "\u0002ABC\u0003"
+  ];
+  for (String test in tests) {
+    print(makePrintable(test));
+    stdout.write(" --> ");
+    String t = "";
+    try {
+      t = bwt(test);
+      print(makePrintable(t));
+    } catch (e) {
+      print("ERROR: ${e.toString()}");
+    }
+    String r = ibwt(t);
+    print(" --> $r\n");
+  }
+}
+
+const String STX = "\u0002";
+const String ETX = "\u0003";
+
+String bwt(String s) {
+  if (s.contains(STX) || s.contains(ETX)) {
+    throw FormatException("String cannot contain STX or ETX");
+  }
+
+  String ss = STX + s + ETX;
+  List<String> table = [];
+  for (int i = 0; i < ss.length; i++) {
+    String before = ss.substring(i);
+    String after = ss.substring(0, i);
+    table.add(before + after);
+  }
+  table.sort();
+
+  return table.map((str) => str[str.length - 1]).join();
+}
+
+String ibwt(String r) {
+  int len = r.length;
+  List<String> table = List.filled(len, "");
+  for (int j = 0; j < len; ++j) {
+    for (int i = 0; i < len; ++i) {
+      table[i] = r[i] + table[i];
+    }
+    table.sort();
+  }
+  for (String row in table) {
+    if (row.endsWith(ETX)) {
+      return row.substring(1, len - 1);
+    }
+  }
+  return "";
+}
+
+String makePrintable(String s) {
+  // substitute ^ for STX and | for ETX to print results
+  return s.replaceAll(STX, "^").replaceAll(ETX, "|");
+}

Task/Burrows-Wheeler-transform/Sidef/burrows-wheeler-transform-2.sidef

@@ -16,28 +16,9 @@ func bwt_sort (String s) {    # O(n * LOOKAHEAD_LEN) space (fast)
 
 func bwt_encode(String s) {
 
-    var bwt    = bwt_sort(s)
-    var ret    = bwt.map {|i| s.slice(i-1, 1) }.join
-    var prefix = s.slice(0, LOOKAHEAD_LEN)
-    var len    = prefix.len
-
-    var idx = 0;
-    for i in (bwt) {
-
-        var lookahead = s.slice(i, len)
-
-        if (lookahead.len < len) {
-            lookahead += s.slice(0, len - lookahead.len)
-        }
-
-        if (lookahead == prefix) {
-            var row = s.rotate(i)
-            if (row == s) {
-                break
-            }
-        }
-        ++idx
-    }
+    var bwt = bwt_sort(s)
+    var ret = bwt.map {|i| s.slice(i-1, 1) }.join
+    var idx = bwt.first_index_by { .is_zero }
 
     return (ret, idx)
 }