2-1 completed

2-1/main.go

@@ -1,7 +1,95 @@
 package main
 
-import "fmt"
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+type Instruction struct {
+	instr int // forward = 0, up = 1, down = 2
+	value int
+}
+
+func (in *Instruction) execute(x, depth int) (int, int) {
+	switch in.instr {
+	case 0: // Forward
+		x += in.value
+	case 1: // Up
+		depth -= in.value
+	case 2: // Down
+		depth += in.value
+	}
+
+	return x, depth
+}
+
+func newInstruction(str string, val int) Instruction {
+	instr := 0
+
+	switch str {
+	case "forward":
+		instr = 0
+	case "up":
+		instr = 1
+	case "down":
+		instr = 2
+	}
+
+	in := Instruction{
+		instr: instr,
+		value: val,
+	}
+	return in
+}
+
+func parseInstruction(instruction string) (Instruction, error) {
+	instr := strings.Split(instruction, " ")
+	part1 := instr[0]
+	part2, err := strconv.Atoi(instr[1])
+	if err != nil {
+		return Instruction{}, err
+	}
+
+	return newInstruction(part1, part2), nil
+}
+
+func readInput(filename string) ([]Instruction, error) {
+	file, err := os.Open(filename)
+	if err != nil {
+		return nil, err
+	}
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+	instructions := make([]Instruction, 0)
+
+	for scanner.Scan() {
+		in, err := parseInstruction(scanner.Text())
+		if err != nil {
+			return nil, err
+		}
+		instructions = append(instructions, in)
+	}
+
+	return instructions, nil
+}
 
 func main() {
-	fmt.Println("Hello world!")
+	ins, err := readInput("input")
+	if err != nil {
+		fmt.Printf("%s", err.Error())
+		return
+	}
+
+	xPos := 0
+	depth := 0
+
+	for i := 0; i < len(ins); i++ {
+		xPos, depth = ins[i].execute(xPos, depth)
+	}
+
+	fmt.Printf("X is now: %d\nDepth is now: %d\nMultiplied is: %d", xPos, depth, (xPos * depth))
 }