June 2018 Update

Task/Move-to-front-algorithm/Julia/move-to-front-algorithm.julia

@@ -0,0 +1,33 @@
+function encodeMTF(str::AbstractString, symtable::Vector{Char}=collect('a':'z'))
+    function encode(ch::Char)
+        r = findfirst(symtable, ch)
+        deleteat!(symtable, r)
+        prepend!(symtable, ch)
+        return r
+    end
+    collect(encode(ch) for ch in str)
+end
+
+function decodeMTF(arr::Vector{Int}, symtable::Vector{Char}=collect('a':'z'))
+    function decode(i::Int)
+        r = symtable[i]
+        deleteat!(symtable, i)
+        prepend!(symtable, r)
+        return r
+    end
+    join(decode(i) for i in arr)
+end
+
+testset = ["broood", "bananaaa", "hiphophiphop"]
+encoded = encodeMTF.(testset)
+decoded = decodeMTF.(encoded)
+for (str, enc, dec) in zip(testset, encoded, decoded)
+    println("Test string: $str\n -> Encoded: $enc\n -> Decoded: $dec")
+end
+
+using Base.Test
+@testset "Decoded string equal to original" begin
+    for (str, dec) in zip(testset, decoded)
+        @test str == dec
+    end
+end