From 5d7c500bf69fcd850a1303d89074c17dfc9df443 Mon Sep 17 00:00:00 2001
From: alexchao26 <alexchaoo@gmail.com>
Date: Sun, 13 Dec 2020 20:54:28 -0500
Subject: [PATCH] 2017-day5: simple jumping around a slice

---
 2017/day05/main.go      | 64 +++++++++++++++++++++++++++++++++++++++++
 2017/day05/main_test.go | 42 +++++++++++++++++++++++++++
 2 files changed, 106 insertions(+)
 create mode 100644 2017/day05/main.go
 create mode 100644 2017/day05/main_test.go

diff --git a/2017/day05/main.go b/2017/day05/main.go
new file mode 100644
index 0000000..a5d99b6
--- /dev/null
+++ b/2017/day05/main.go
@@ -0,0 +1,64 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"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)
+
+	if part == 1 {
+		ans := part1(util.ReadFile("./input.txt"))
+		fmt.Println("Output:", ans)
+	} else {
+		ans := part2(util.ReadFile("./input.txt"))
+		fmt.Println("Output:", ans)
+	}
+}
+
+func part1(input string) int {
+	maze := parseInput(input)
+
+	var index, steps int
+	for index >= 0 && index < len(maze) {
+		maze[index]++
+		index += maze[index] - 1
+		steps++
+	}
+
+	return steps
+}
+
+func part2(input string) int {
+	maze := parseInput(input)
+
+	var index, steps int
+	for index >= 0 && index < len(maze) {
+		nextIndex := maze[index]
+		if maze[index] >= 3 {
+			maze[index]--
+		} else {
+			maze[index]++
+		}
+		index += nextIndex
+		steps++
+	}
+
+	return steps
+}
+
+func parseInput(input string) (ans []int) {
+	lines := strings.Split(input, "\n")
+	for _, l := range lines {
+		ans = append(ans, mathutil.StrToInt(l))
+	}
+	return ans
+}
diff --git a/2017/day05/main_test.go b/2017/day05/main_test.go
new file mode 100644
index 0000000..920f8e6
--- /dev/null
+++ b/2017/day05/main_test.go
@@ -0,0 +1,42 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/alexchao26/advent-of-code-go/util"
+)
+
+func Test_part1(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		want  int
+	}{
+		{"actual", util.ReadFile("input.txt"), 373160},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := part1(tt.input); got != tt.want {
+				t.Errorf("part1() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func Test_part2(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		want  int
+	}{
+		{"example", "0\n3\n0\n1\n-3", 10},
+		{"actual", util.ReadFile("input.txt"), 26395586},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := part2(tt.input); got != tt.want {
+				t.Errorf("part2() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}