Initial commit

3.jl

@@ -0,0 +1,61 @@
+include("utils.jl")
+
+function parse_input(filename)
+    input_lines = collect(non_empty_lines(filename))
+    width = length(input_lines[1])
+    integers = map(x->parse(Int, x, base = 2), input_lines)
+    (integers, width)
+end
+
+function most_common_bit(integers, width)
+    score = zeros(Int, width)
+    for int in integers
+        for index in 1:width
+            score[index] += ((int >> (index-1) & 1) - 0.5) * 2
+        end
+    end
+    map(map(sign, score)) do x
+        if x == 0
+            1
+        else
+            x
+        end
+    end
+end
+
+function solution3_1()
+    integers, width = parse_input("3.data")
+
+    score = most_common_bit(integers, width)
+
+    result = 0
+    cresult = 0
+    for i in 1:width
+        result += ((score[i] + 1) >> 1) << (i - 1)
+        cresult += (((score[i] * -1) + 1) >> 1) << (i - 1)
+    end
+    (result, cresult, result * cresult)
+end
+
+function filterdata(integers, width, score_factor)
+    ints = copy(integers)
+    for i in reverse(1:width)
+        score = most_common_bit(ints, width) * score_factor
+        ints = filter(ints) do x
+            (x & (1 << (i - 1))) >> (i - 1) == (score[i] + 1) >> 1
+        end
+        if length(ints) == 1
+            break
+        end
+    end
+    ints[1]
+end
+
+function solution3_2()
+    integers, width = parse_input("3.data")
+    oxy = filterdata(integers, width, 1)
+    co2 = filterdata(integers, width, -1)
+    (oxy, co2, oxy * co2)
+end
+
+solution3_2()