add day3

day3/day3.jl

@@ -0,0 +1,70 @@
+#!/usr/bin/env julia
+
+using Test
+
+function priority(char)
+  v = Int(char)
+  if v <= Int('Z')
+    return v - Int('A') + 27
+  else
+    return v - Int('a') + 1
+  end
+end
+
+function rucksack_errors(infile)
+  psum = 0
+
+  open(infile, "r") do io
+    for line in eachline(io)
+      n = length(line)
+      a = Set{Int32}()
+      b = Set{Int32}()
+      for c in line[1:Int(n/2)]
+        push!(a, priority(c))
+      end
+      for c in line[Int(n/2)+1:n]
+        push!(b, priority(c))
+      end
+      psum += pop!(intersect(a, b))
+    end
+  end
+
+  return psum
+end
+
+function rucksack_badges(infile)
+  psum = 0
+
+  open(infile, "r") do io
+    for lines in Iterators.partition(eachline(io), 3)
+      all = intersect!(Set(lines[1]), Set(lines[2]), Set(lines[3]))
+      psum += priority(pop!(all))
+    end
+  end
+
+  return psum
+end
+
+
+function test()
+  @testset "elf rucksack errors" verbose=true begin
+    @test rucksack_errors("example.txt") == 157
+    @test rucksack_errors("input.txt") == 8394
+  end
+  @testset "elf rucksack badges" verbose=true begin
+    @test rucksack_badges("example.txt") == 70
+    @test rucksack_badges("input.txt") == 2413
+  end
+end
+
+function main()
+  if size(ARGS, 1) == 0
+    test()
+  else
+    infile = ARGS[1]
+    println("infile = ", infile)
+    println("error priority sum: ", rucksack_errors(infile))
+  end
+end
+
+main()