Add exercise: hamming (JuliaLang#12)

config.json

@@ -5,6 +5,15 @@
   "active": false,
   "test_pattern": "TODO",
   "exercises": [
+    {
+      "slug": "hamming",
+      "difficulty": 1,
+      "topics": [
+        "generators",
+        "strings",
+        "exceptions"
+      ]
+    },
     {
       "slug": "difference-of-squares",
       "difficulty": 1,

exercises/hamming/example.jl

@@ -0,0 +1,5 @@
+function distance(s1::AbstractString, s2::AbstractString)
+    length(s1) != length(s2) && throw(ArgumentError("Sequences must have the same length"))
+
+    reduce(+, 0, a != b for (a, b) in zip(s1, s2))
+end

exercises/hamming/hamming.jl

@@ -0,0 +1,3 @@
+function distance(s1::AbstractString, s2::AbstractString)
+
+end

exercises/hamming/runtests.jl

@@ -0,0 +1,42 @@
+using Base.Test
+
+include("hamming.jl")
+
+@testset "identical strands" begin
+    @test distance("A", "A") == 0
+    @test distance("GGACTGA", "GGACTGA") == 0
+end
+
+@testset "complete distance" begin
+    @test distance("A", "G") == 1
+    @test distance("AG", "CT") == 2
+end
+
+@testset "small distance" begin
+    @test distance("AT", "CT") == 1
+    @test distance("GGACG", "GGTCG") == 1
+    @test distance("ACCAGGG", "ACTATGG") == 2
+end
+
+@testset "non-unique characters" begin
+    @test distance("AGA", "AGG") == 1
+    @test distance("AGG", "AGA") == 1
+end
+
+@testset "same nucleotides in different positions" begin
+    @test distance("TAG", "GAT") == 2
+end
+
+@testset "large distance" begin
+    @test distance("GATACA", "GCATAA") == 4
+    @test distance("GGACGGATTCTG", "AGGACGGATTCT") == 9
+end
+
+@testset "empty strands" begin
+    @test distance("", "") == 0
+end
+
+@testset "different strand lengths" begin
+    @test_throws ArgumentError distance("AATG", "AAA")
+    @test_throws ArgumentError distance("ATA", "AGTG")
+end