June 2018 Update

Task/Look-and-say-sequence/BASIC256/look-and-say-sequence.basic256

@@ -0,0 +1,25 @@
+# look and say
+
+dim a$(2)
+
+i = 0  # input string index
+
+a$[i] = "1"
+
+print a$[i]
+
+for n=1 to 10
+  j = 1 - i  # output string index
+  a$[j] = ""
+  k = 1
+  while (k <= length(a$[i]))
+    k0 = k + 1
+    while ((k0 <= length(a$[i])) and (mid(a$[i], k, 1) = mid(a$[i], k0, 1)))
+      k0 = k0 + 1
+    end while
+    a$[j] += string(k0 - k) + mid(a$[i], k, 1)
+    k = k0
+  end while
+  i = j
+  print a$[j]
+next n

Task/Look-and-say-sequence/C++/look-and-say-sequence.cpp

@@ -1,32 +1,32 @@
-#include <string>
-#include <sstream>
-
-std::string lookandsay(const std::string &s)
-{
-  std::ostringstream r;
-
-  for (unsigned int i = 0; i != s.length(); ) {
-    unsigned int new_i = s.find_first_not_of(s[i], i+1);
-    if (new_i == std::string::npos)
-      new_i = s.length();
-
-    r << new_i - i << s[i];
-    i = new_i;
-  }
-  return r.str();
-}
-
 #include <iostream>
+#include <sstream>
+#include <string>
+
+std::string lookandsay(const std::string& s)
+{
+    std::ostringstream r;
+
+    for (std::size_t i = 0; i != s.length();) {
+        auto new_i = s.find_first_not_of(s[i], i + 1);
+
+        if (new_i == std::string::npos)
+            new_i = s.length();
+
+        r << new_i - i << s[i];
+        i = new_i;
+    }
+    return r.str();
+}
 
 int main()
 {
-  std::string laf = "1";
+    std::string laf = "1";
 
-  std::cout << laf << std::endl;
-  for (int i = 0; i < 10; i++) {
-    laf = lookandsay(laf);
     std::cout << laf << std::endl;
-  }
+    for (int i = 0; i < 10; ++i) {
+        laf = lookandsay(laf);
+        std::cout << laf << std::endl;
+    }
 
-  return 0;
+    return 0;
 }

Task/Look-and-say-sequence/Ceylon/look-and-say-sequence.ceylon

@@ -0,0 +1,28 @@
+shared void run() {
+	
+    function lookAndSay(Integer|String input) {
+
+        variable value digits = if (is Integer input) then input.string else input;
+        value builder = StringBuilder();
+
+        while (exists currentChar = digits.first) {
+            if (exists index = digits.firstIndexWhere((char) => char != currentChar)) {
+                digits = digits[index...];
+                builder.append("``index````currentChar``");
+            }
+            else {
+                builder.append("``digits.size````currentChar``");
+                break;
+            }
+        }
+
+        return builder.string;
+    }
+
+    variable String|Integer result = 1;
+    print(result);
+    for (i in 1..14) {
+        result = lookAndSay(result);
+        print(result);
+    }
+}

Task/Look-and-say-sequence/Perl-6/look-and-say-sequence.pl6

@@ -1 +1 @@
-.say for '1', *.subst(/(.)$0*/, { .chars ~ .[0] }, :g) ... *;
+.say for ('1', *.subst(/(.)$0*/, { .chars ~ .[0] }, :g) ... *)[^15];

Task/Look-and-say-sequence/Q/look-and-say-sequence.q

@@ -0,0 +1,2 @@
+las:{{raze string[count@'x],'@'[;0]x:where[differ x]_x}\[x;1#"1"]}
+las 8

Task/Look-and-say-sequence/Scala/look-and-say-sequence-1.scala

@@ -1,11 +1,27 @@
-def lookAndSay(seed: BigInt) = {
-  val s = seed.toString
-  ( 1 until s.size).foldLeft((1, s(0), new StringBuilder)) {
-    case ((len, c, sb), index) if c != s(index) => sb.append(len); sb.append(c); (1, s(index), sb)
-    case ((len, c, sb), _) => (len + 1, c, sb)
-  } match {
-    case (len, c, sb) => sb.append(len); sb.append(c); BigInt(sb.toString)
-  }
-}
+import scala.annotation.tailrec
 
-def lookAndSayIterator(seed: BigInt) = Iterator.iterate(seed)(lookAndSay)
+object LookAndSay extends App {
+
+  loop(10, "1")
+
+  @tailrec
+  private def loop(n: Int, num: String): Unit = {
+    println(num)
+    if (n <= 0) () else loop(n - 1, lookandsay(num))
+  }
+
+  private def lookandsay(number: String): String = {
+    val result = new StringBuilder
+
+    @tailrec
+    def loop(numberString: String, repeat: Char, times: Int): String =
+      if (numberString.isEmpty) result.toString()
+      else if (numberString.head != repeat) {
+        result.append(times).append(repeat)
+        loop(numberString.tail, numberString.head, 1)
+      } else loop(numberString.tail, numberString.head, times + 1)
+
+    loop(number.tail + " ", number.head, 1)
+  }
+
+}

Task/Look-and-say-sequence/Scala/look-and-say-sequence-2.scala

@@ -1,17 +1,11 @@
-object Main extends App {
-
-  def lookAndSay(previous: List[BigInt]): Stream[List[BigInt]] = {
-
-    def next(num: List[BigInt]): List[BigInt] = num match {
-      case Nil => Nil
-      case head :: Nil => 1 :: head :: Nil
-      case head :: tail =>
-        val size = (num takeWhile (_ == head)).size
-        List(BigInt(size), head) ::: next(num.drop(size))
-    }
-    val x = next(previous)
-    x #:: lookAndSay(x)
+def lookAndSay(seed: BigInt) = {
+  val s = seed.toString
+  ( 1 until s.size).foldLeft((1, s(0), new StringBuilder)) {
+    case ((len, c, sb), index) if c != s(index) => sb.append(len); sb.append(c); (1, s(index), sb)
+    case ((len, c, sb), _) => (len + 1, c, sb)
+  } match {
+    case (len, c, sb) => sb.append(len); sb.append(c); BigInt(sb.toString)
   }
-
-  (lookAndSay(1 :: Nil) take 10).foreach(s => println(s.mkString("")))
 }
+
+def lookAndSayIterator(seed: BigInt) = Iterator.iterate(seed)(lookAndSay)

Task/Look-and-say-sequence/Scala/look-and-say-sequence-3.scala

@@ -0,0 +1,17 @@
+object Main extends App {
+
+  def lookAndSay(previous: List[BigInt]): Stream[List[BigInt]] = {
+
+    def next(num: List[BigInt]): List[BigInt] = num match {
+      case Nil => Nil
+      case head :: Nil => 1 :: head :: Nil
+      case head :: tail =>
+        val size = (num takeWhile (_ == head)).size
+        List(BigInt(size), head) ::: next(num.drop(size))
+    }
+    val x = next(previous)
+    x #:: lookAndSay(x)
+  }
+
+  (lookAndSay(1 :: Nil) take 10).foreach(s => println(s.mkString("")))
+}