diff --git a/2017/day08/main.go b/2017/day08/main.go
new file mode 100644
index 0000000..124fc54
--- /dev/null
+++ b/2017/day08/main.go
@@ -0,0 +1,96 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"math"
+	"strings"
+
+	"github.com/alexchao26/advent-of-code-go/mathutil"
+
+	"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 := calcRegisters(util.ReadFile("./input.txt"), part)
+	util.CopyToClipboard(fmt.Sprintf("%v", ans))
+	fmt.Println("Output:", ans)
+}
+
+func calcRegisters(input string, part int) int {
+	instructions := parseInput(input)
+
+	registers := map[string]int{}
+	var highestEverRegister int // for part 2
+	for _, inst := range instructions {
+		registerVal := registers[inst.conditional[0]]
+		compareVal := mathutil.StrToInt(inst.conditional[2])
+		var conditionalResult bool
+		switch inst.conditional[1] {
+		case "==":
+			conditionalResult = registerVal == compareVal
+		case "!=":
+			conditionalResult = registerVal != compareVal
+		case "<":
+			conditionalResult = registerVal < compareVal
+		case ">":
+			conditionalResult = registerVal > compareVal
+		case "<=":
+			conditionalResult = registerVal <= compareVal
+		case ">=":
+			conditionalResult = registerVal >= compareVal
+		default:
+			panic("unhandled operator")
+		}
+		if conditionalResult {
+			registers[inst.registerName] += inst.diff
+		}
+		highestEverRegister = mathutil.MaxInt(highestEverRegister, registers[inst.registerName])
+	}
+
+	largestFinalRegister := -math.MaxInt32
+	for _, v := range registers {
+		largestFinalRegister = mathutil.MaxInt(largestFinalRegister, v)
+	}
+
+	if part == 1 {
+		return largestFinalRegister
+	}
+	return highestEverRegister
+}
+
+type instruction struct {
+	registerName string    // register to modify
+	diff         int       // if instruction is a dec, multiply by -1
+	conditional  [3]string // contains all 3 parts @ end of each instruction
+}
+type compareFunc func(value int) bool
+
+func parseInput(input string) []instruction {
+	lines := strings.Split(input, "\n")
+	var instructions []instruction
+
+	for _, l := range lines {
+		parts := strings.Split(l, " ")
+		if len(parts) != 7 {
+			panic("parts len to seven")
+		}
+		inst := instruction{
+			registerName: parts[0],
+			diff:         mathutil.StrToInt(parts[2]),
+			conditional:  [3]string{parts[4], parts[5], parts[6]},
+		}
+		if parts[1] == "dec" {
+			inst.diff *= -1
+		}
+
+		instructions = append(instructions, inst)
+	}
+
+	return instructions
+}
diff --git a/2017/day08/main_test.go b/2017/day08/main_test.go
new file mode 100644
index 0000000..c057930
--- /dev/null
+++ b/2017/day08/main_test.go
@@ -0,0 +1,33 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/alexchao26/advent-of-code-go/util"
+)
+
+var example = `b inc 5 if a > 1
+a inc 1 if b < 5
+c dec -10 if a >= 1
+c inc -20 if c == 10`
+
+func Test_calcRegisters(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		part  int
+		want  int
+	}{
+		{"example-part1", example, 1, 1},
+		{"actual-part1", util.ReadFile("input.txt"), 1, 4066},
+		{"example-part2", example, 2, 10},
+		{"actual-part2", util.ReadFile("input.txt"), 2, 4829},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := calcRegisters(tt.input, tt.part); got != tt.want {
+				t.Errorf("part1() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}