September 2017 Update

Task/Look-and-say-sequence/00DESCRIPTION

@@ -19,6 +19,14 @@ The   [[wp:Look and say sequence|Look and say sequence]]   is a recurs
 Write a program to generate successive members of the look-and-say sequence.
 
 
+;Related tasks:
+*   [[Fours is the number of letters in the ...]]
+*   [[Number names]]
+*   [[Self-describing numbers]]
+*   [[Self-referential sequence]]
+*   [[Spelling of ordinal numbers]]
+
+
 ;See also:
 *   [https://www.youtube.com/watch?v=ea7lJkEhytA Look-and-Say Numbers (feat John Conway)], A Numberphile Video.
 *   This task is related to, and an application of, the [[Run-length encoding]] task.

Task/Look-and-say-sequence/Gambas/look-and-say-sequence.gambas

@@ -0,0 +1,25 @@
+Public Sub Main()
+Dim i, j, cnt As Integer
+Dim txt$, curr$, result$ As String
+
+txt$ = "1211"
+i = 1
+
+Print "Sequence: " & txt$ & " = ";
+  Repeat
+    j = 1
+    result$ = ""
+      Repeat
+        curr$ = Mid(txt$, j, 1)
+        cnt = 0
+          Repeat
+            Inc cnt
+            Inc j
+          Until Mid(txt$, j, 1) <> curr$
+        result$ &= Str(cnt) & curr$
+      Until j > Len(txt$)
+    Print result$
+    txt$ = result$
+    Dec i
+  Until i <= 0
+End

Task/Look-and-say-sequence/Julia/look-and-say-sequence.julia

@@ -0,0 +1,27 @@
+# v0.6
+
+function lookandsay(n::String)
+    rst = IOBuffer()
+    i, c = 1, 1
+    while i ≤ length(n)
+        if i != length(n) && n[i] == n[i+1]
+            c += 1
+        else
+            print(rst, c, n[i])
+            c = 1
+        end
+        i += 1
+    end
+    return String(take!(rst))
+end
+
+function lookandsayseq(n::Integer)
+    rst = Array{String}(n)
+    rst[1] = "1"
+    for i in 2:n
+        rst[i] = lookandsay(rst[i-1])
+    end
+    return rst
+end
+
+println(lookandsayseq(10))

Task/Look-and-say-sequence/Kotlin/look-and-say-sequence.kotlin

@@ -0,0 +1,25 @@
+// version 1.0.6
+
+fun lookAndSay(s: String): String {
+    val sb = StringBuilder()
+    var digit = s[0]
+    var count = 1
+    for (i in 1 until s.length) {
+        if (s[i] == digit)
+            count++
+        else {
+            sb.append("$count$digit")
+            digit = s[i]
+            count = 1
+        }
+    }
+    return sb.append("$count$digit").toString()
+}
+
+fun main(args: Array<String>) {
+    var las = "1"
+    for (i in 1..15) {
+        println(las)
+        las = lookAndSay(las)
+    }
+}

Task/Look-and-say-sequence/Phix/look-and-say-sequence.phix

@@ -0,0 +1,22 @@
+function lookandsay(string s)
+string res = ""
+integer p = s[1], c = 1
+    for i=2 to length(s) do
+        if p=s[i] then
+            c += 1
+        else
+            res &= sprintf("%d%s",{c,p})
+            p = s[i]
+            c = 1
+        end if
+    end for
+    res &= sprintf("%d%s",{c,p})
+    return res
+end function
+
+string s = "1"
+?s
+for i=1 to 10 do
+    s = lookandsay(s)
+    ?s
+end for

Task/Look-and-say-sequence/Zkl/look-and-say-sequence.zkl

@@ -0,0 +1,8 @@
+fcn lookAndSay(seed){ // numeric String --> numeric String
+   len,c:=[1..seed.len()-1].reduce(fcn([(len,c)]lc,index,s,sb){
+      if(c!=s[index]) { sb.write(len); sb.write(c); lc.clear(1,s[index]) }
+      else lc.clear(len+1,c);
+   },L(1,seed[0]), seed,sb:=Sink(String));
+   sb.write(len); sb.write(c);
+   sb.close();
+}