Day 1 in Go

Purely for curiosity/benchmarking-against-identical-Rust-version reasons

Spoilers: Rust is somewhat faster than Go and very much faster than .net
...though presumably .net's problem is purely startup time

.gitignore

@@ -3,3 +3,4 @@
 *.user
 /bin/
 /obj/
+*.exe

go.mod

@@ -0,0 +1,3 @@
+module aoc2021
+
+go 1.17

main.go

@@ -0,0 +1,7 @@
+package main
+
+import "aoc2021/src"
+
+func main() {
+	src.Day01()
+}

src/01.go

@@ -0,0 +1,69 @@
+package src
+
+import (
+	"fmt"
+	"io/ioutil"
+	"strconv"
+	"strings"
+)
+
+func Day01() {
+	fileBytes, fileErr := ioutil.ReadFile("inputs/01.txt")
+	if fileErr != nil {
+		panic(fileErr)
+	}
+
+	fileStr := string(fileBytes)
+	fileLines := strings.Split(strings.ReplaceAll(fileStr, "\r", ""), "\n")
+	fileInts := make([]int, len(fileLines))
+	var err error
+	for idx, line := range fileLines {
+		fileInts[idx], err = strconv.Atoi(line)
+		if err != nil {
+			panic(err)
+		}
+	}
+	part1(fileInts)
+	part2(fileInts)
+}
+
+func part1(depths []int) {
+	lastDepth := 0
+	numIncreased := -1
+
+	for _, depth := range depths {
+		if depth > lastDepth {
+			numIncreased++
+		}
+
+		lastDepth = depth
+	}
+
+	fmt.Println("part1: increased:", numIncreased)
+}
+
+func part2(depths []int) {
+	lastTotal := 0
+	numIncreased := -1
+
+	num1 := -1
+	num2 := -1
+	num3 := -1
+
+	for _, depth := range depths {
+		num1 = num2
+		num2 = num3
+		num3 = depth
+		if num1 < 0 || num2 < 0 || num3 < 0 {
+			continue
+		}
+
+		total := num1 + num2 + num3
+		if total > lastTotal {
+			numIncreased++
+		}
+		lastTotal = total
+	}
+
+	fmt.Println("part2: increased:", numIncreased)
+}