add day 2 results

day-2/main.go

@@ -0,0 +1,111 @@
+/* Day 2: Dive! */
+package main
+
+import (
+	"AoC2021/utils/timer"
+	"bufio"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+func check(e error) {
+	if e != nil {
+		fmt.Println("Oh snap!")
+		panic(e)
+	}
+}
+
+func main() {
+	fmt.Println("--- Day 2: Dive! ---")
+	timer.Start()
+	part1()
+	timer.Tick()
+	fmt.Println()
+
+	part2()
+	timer.Tick()
+	fmt.Println()
+}
+
+func part1() {
+	fmt.Println("* Part 1 *")
+	fmt.Println(" Goal: Calculate the horizontal position and depth you would have after following the planned course")
+	fmt.Println(" Answer: What do you get if you multiply your final horizontal position by your final depth?")
+
+	input, err := os.Open("./input.txt")
+	defer input.Close()
+	check(err)
+
+	scanner := bufio.NewScanner(input)
+	lines := 0
+	posX, posY := 0, 0
+
+	for scanner.Scan() {
+		str := scanner.Text()
+		values := strings.Fields(str)
+		if len(values) < 2 {
+			panic("read invalid line: " + str)
+		}
+		direction := values[0]
+		units, err := strconv.Atoi(values[1])
+		check(err)
+		switch direction {
+		case "forward":
+			posX += units
+		case "down":
+			posY += units
+		case "up":
+			posY -= units
+		default:
+			panic("Invalid direction: " + direction)
+		}
+
+		lines++
+	}
+
+	fmt.Printf("Read %d lines from input\n", lines)
+	fmt.Printf("The final position is (%d, %d) for an answer of %d\n", posX, posY, posX*posY)
+}
+
+func part2() {
+	fmt.Println("* Part 2 *")
+	fmt.Println(" Goal: Using this new interpretation of the commands, calculate the horizontal position and depth you would have after following the planned course")
+	fmt.Println(" Answer: What do you get if you multiply your final horizontal position by your final depth?")
+
+	input, err := os.Open("./input.txt")
+	defer input.Close()
+	check(err)
+
+	scanner := bufio.NewScanner(input)
+	lines := 0
+	posX, posY, aim := 0, 0, 0
+
+	for scanner.Scan() {
+		str := scanner.Text()
+		values := strings.Fields(str)
+		if len(values) < 2 {
+			panic("read invalid line: " + str)
+		}
+		direction := values[0]
+		units, err := strconv.Atoi(values[1])
+		check(err)
+		switch direction {
+		case "forward":
+			posX += units
+			posY += units * aim
+		case "down":
+			aim += units
+		case "up":
+			aim -= units
+		default:
+			panic("Invalid direction: " + direction)
+		}
+
+		lines++
+	}
+
+	fmt.Printf("Read %d lines from input\n", lines)
+	fmt.Printf("The final position is (%d, %d) for an answer of %d\n", posX, posY, posX*posY)
+}

day-2/main_test.go

@@ -0,0 +1,11 @@
+package main
+
+import (
+	assert "AoC2021/utils/testing"
+	"testing"
+)
+
+func TestDay2(t *testing.T) {
+	assert.IsTrue(t, true, "cool")
+	assert.StrEquals(t, "foo", "bar", "baz")
+}

main_test.go.template

@@ -0,0 +1,11 @@
+package main
+
+import (
+	assert "AoC2021/utils/testing"
+	"testing"
+)
+
+func TestDay#DAY#(t *testing.T) {
+	assert.IsTrue(t, true, "cool")
+	assert.StrEquals(t, "foo", "bar", c.msg)
+}

makefile

@@ -1,8 +1,11 @@
-default: build day=1
+default:
 	# This is my 2021 Advent of Code project
 
 init:
-	mkdir day-$(day); sed 's/#DAY#/$(day)/g' main.go.template | sed 's/#TITLE#/$(title)/g' > day-$(day)/main.go; touch day-$(day)/input.txt
+	mkdir day-$(day)
+	sed 's/#DAY#/$(day)/g' main.go.template | sed 's/#TITLE#/$(title)/g' > day-$(day)/main.go
+	sed 's/#DAY#/$(day)/g' main_test.go.template > day-$(day)/main_test.go
+	touch day-$(day)/input.txt;
 
 build:
 	cd day-$(day); go run .

utils/testing/assert.go

@@ -2,6 +2,13 @@ package assert
 
 import "testing"
 
+func IsTrue(t *testing.T, expr bool, message string) {
+	if expr != true {
+		t.Logf("Expected true but got false: %s", message)
+		t.Fail()
+	}
+}
+
 func StrEquals(t *testing.T, actual, expected, message string) {
 	if actual != expected {
 		t.Logf("Expected value '%s' but got '%s': %s", expected, actual, message)