From 49b68602ffa019716e82d86345568a9ccfcb08d1 Mon Sep 17 00:00:00 2001
From: tholok97 <thomas.lokkeborg@mimer.no>
Date: Tue, 8 Dec 2020 19:57:27 +0100
Subject: [PATCH] day 8 in go

---
 days/day-08/solutions/tholok97.go | 94 +++++++++++++++++++++++++++++++
 days/day-08/test.sh               |  1 +
 2 files changed, 95 insertions(+)
 create mode 100644 days/day-08/solutions/tholok97.go

diff --git a/days/day-08/solutions/tholok97.go b/days/day-08/solutions/tholok97.go
new file mode 100644
index 00000000..c06ab115
--- /dev/null
+++ b/days/day-08/solutions/tholok97.go
@@ -0,0 +1,94 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"regexp"
+	"strconv"
+)
+
+type instruction struct {
+	arg int
+	op  string
+}
+
+func main() {
+	scanner := bufio.NewScanner(os.Stdin)
+
+	instructions := make([]instruction, 0)
+
+	for scanner.Scan() {
+		line := scanner.Text()
+
+		re := regexp.MustCompile(`^(nop|acc|jmp) ([+-]\d+)$`)
+		matches := re.FindStringSubmatch(line)
+
+		arg, err := strconv.Atoi(matches[2])
+
+		if err != nil {
+			panic("Misbehaving number")
+		}
+
+		instructions = append(instructions, instruction{
+			op:  matches[1],
+			arg: arg,
+		})
+	}
+
+	_, accumulator := run(instructions)
+
+	fmt.Println(accumulator)
+
+	for i := 0; i < len(instructions); i++ {
+		swap := instructions[i].op
+
+		switch swap {
+		case "jmp":
+			instructions[i].op = "nop"
+		case "nop":
+			instructions[i].op = "jmp"
+		default:
+			continue
+		}
+
+		isInfinite, accumulator := run(instructions)
+
+		if !isInfinite {
+			fmt.Println(accumulator)
+            break
+		}
+
+		instructions[i].op = swap
+	}
+}
+
+func run(instructions []instruction) (isinfinite bool, accumulator int) {
+	curr := 0
+
+	visited := make([]bool, len(instructions))
+
+	for {
+		if curr == len(instructions) {
+			return false, accumulator
+		}
+
+		if visited[curr] {
+			return true, accumulator
+		}
+
+		visited[curr] = true
+
+		ins := instructions[curr]
+
+		switch ins.op {
+		case "acc":
+			accumulator += ins.arg
+			curr++
+		case "nop":
+			curr++
+		case "jmp":
+			curr += ins.arg
+		}
+	}
+}
diff --git a/days/day-08/test.sh b/days/day-08/test.sh
index b5be87c9..be8072ec 100755
--- a/days/day-08/test.sh
+++ b/days/day-08/test.sh
@@ -6,4 +6,5 @@ D=$(dirname $(realpath $0))
 
 echo ""
 echo "--- Day 8: Handheld Halting ---"
+$D/../../languages/go.sh $D/input.txt $D/output.txt $D/solutions/tholok97.go
 echo ""