diff --git a/2016/day06/main.go b/2016/day06/main.go
new file mode 100644
index 0000000..abac5e5
--- /dev/null
+++ b/2016/day06/main.go
@@ -0,0 +1,63 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"math"
+	"strings"
+
+	"github.com/alexchao26/advent-of-code-go/util"
+)
+
+func main() {
+	var part int
+	flag.IntVar(&part, "part", 1, "part 1 or 2")
+	flag.Parse()
+	fmt.Println("Running part", part)
+
+	ans := signalsAndNoise(util.ReadFile("./input.txt"), part)
+	fmt.Println("Output:", ans)
+}
+
+func signalsAndNoise(input string, part int) string {
+	var grid [][]string
+	for _, line := range strings.Split(input, "\n") {
+		grid = append(grid, strings.Split(line, ""))
+	}
+
+	var indexMaps []map[string]int
+	for col := 0; col < len(grid[0]); col++ {
+		indexMaps = append(indexMaps, map[string]int{})
+		for row := 0; row < len(grid); row++ {
+			char := grid[row][col]
+			indexMaps[col][char]++
+		}
+	}
+
+	var mostVersion string  // part 1
+	var leastVersion string // part 2
+	for col := 0; col < len(indexMaps); col++ {
+		var (
+			mostChar  string
+			mostLen   int
+			leastChar string
+			leastLen  int = math.MaxInt32
+		)
+		for k, count := range indexMaps[col] {
+			if count > mostLen {
+				mostLen = count
+				mostChar = k
+			}
+			if count < leastLen {
+				leastLen = count
+				leastChar = k
+			}
+		}
+		mostVersion += mostChar
+		leastVersion += leastChar
+	}
+	if part == 1 {
+		return mostVersion
+	}
+	return leastVersion
+}
diff --git a/2016/day06/main_test.go b/2016/day06/main_test.go
new file mode 100644
index 0000000..daebf5c
--- /dev/null
+++ b/2016/day06/main_test.go
@@ -0,0 +1,45 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/alexchao26/advent-of-code-go/util"
+)
+
+var example = `eedadn
+drvtee
+eandsr
+raavrd
+atevrs
+tsrnev
+sdttsa
+rasrtv
+nssdts
+ntnada
+svetve
+tesnvt
+vntsnd
+vrdear
+dvrsen
+enarar`
+
+func Test_signalsAndNoise(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		part  int
+		want  string
+	}{
+		{"example", example, 1, "easter"},
+		{"actual", util.ReadFile("input.txt"), 1, "afwlyyyq"},
+		{"example", example, 2, "advent"},
+		{"actual", util.ReadFile("input.txt"), 2, "bhkzekao"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := signalsAndNoise(tt.input, tt.part); got != tt.want {
+				t.Errorf("signalsAndNoise() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}