d3

d3/d3.go

@@ -0,0 +1,38 @@
+package d3
+
+import (
+	"strconv"
+	"strings"
+)
+
+func D3(input string) int64 {
+	binaries := strings.Split(strings.TrimSpace(input), "\n")
+
+	ones := make([]int, len(binaries[0]))
+
+	for _, binary := range binaries {
+		for position, bit := range binary {
+			if byte(bit) == '1' {
+				ones[position]++
+			}
+		}
+	}
+
+	gamma := make([]string, len(ones))
+	epsilon := make([]string, len(ones))
+
+	for pos, oneCount := range ones {
+		if oneCount > len(binaries)/2 {
+			gamma[pos] = "1"
+			epsilon[pos] = "0"
+		} else {
+			gamma[pos] = "0"
+			epsilon[pos] = "1"
+		}
+	}
+
+	gammaNum, _ := strconv.ParseInt(strings.Join(gamma, ""), 2, 64)
+	epsilonNum, _ := strconv.ParseInt(strings.Join(epsilon, ""), 2, 64)
+
+	return gammaNum * epsilonNum
+}

d3/d3_test.go

@@ -0,0 +1,25 @@
+package d3
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestD3(t *testing.T) {
+	input := `
+00100
+11110
+10110
+10111
+10101
+01111
+00111
+11100
+10000
+11001
+00010
+01010`
+
+	assert.EqualValues(t, 198, D3(input))
+}