From 81f11c52ef9ee2ecfe07a9b39c1d8767fade23a7 Mon Sep 17 00:00:00 2001
From: Gregory <neogen570@gmail.com>
Date: Tue, 8 Feb 2022 21:38:01 +0200
Subject: [PATCH] d3

---
 d3/d3.go      | 38 ++++++++++++++++++++++++++++++++++++++
 d3/d3_test.go | 25 +++++++++++++++++++++++++
 2 files changed, 63 insertions(+)
 create mode 100644 d3/d3.go
 create mode 100644 d3/d3_test.go

diff --git a/d3/d3.go b/d3/d3.go
new file mode 100644
index 0000000..f7d9905
--- /dev/null
+++ b/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
+}
diff --git a/d3/d3_test.go b/d3/d3_test.go
new file mode 100644
index 0000000..9a0e844
--- /dev/null
+++ b/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))
+}