2024 Day 3 Complete!

2024/day03/main.go

@@ -0,0 +1,102 @@
+package main
+
+import (
+	"fmt"
+	"regexp"
+	"strings"
+
+	helpers "git.bullercodeworks.com/brian/adventofcode/helpers"
+)
+
+func main() {
+	inp := helpers.StdinToString()
+	part1(inp)
+	part2(inp)
+}
+
+func part1(inp string) {
+	mulCmds := regexp.MustCompile(`mul\(\d\d?\d?,\d\d?\d?\)`)
+	cmds := mulCmds.FindAllString(inp, -1)
+	var total int
+	for _, v := range cmds {
+		var num1, num2 int
+		fmt.Sscanf(v, "mul(%d,%d)", &num1, &num2)
+		fmt.Printf("%s -> %d * %d = %d\n", v, num1, num2, num1*num2)
+		total = total + (num1 * num2)
+	}
+	fmt.Println("# Part 1")
+	fmt.Printf("Total: %d\n\n", total)
+}
+
+func part2(inp string) {
+	var total int
+	do, run := true, true
+	for run {
+		var cmd Command
+		prev := inp
+		cmd, inp = getNextCommand(inp)
+		fmt.Println("Processing Command:", cmd)
+		fmt.Println("Remainder:", inp)
+		if prev == inp {
+			panic("Remainder didn't change")
+		}
+		run = len(inp) > 0
+		switch cmd.Name {
+		case "mul":
+			if do {
+				total = total + cmd.Run()
+			}
+		case "do":
+			do = true
+		case "don't":
+			do = false
+		}
+	}
+	fmt.Println("# Part 2")
+	fmt.Printf("Total: %d\n", total)
+}
+
+type Command struct {
+	Name   string
+	Values []int
+}
+
+func (c *Command) Run() int {
+	if c.Name == "mul" {
+		return c.Values[0] * c.Values[1]
+	}
+	return 0
+}
+
+func (c Command) String() string {
+	switch c.Name {
+	case "mul":
+		return fmt.Sprintf("%s(%d,%d)", c.Name, c.Values[0], c.Values[1])
+	default:
+		return fmt.Sprintf("%s()", c.Name)
+	}
+}
+
+func getNextCommand(inp string) (Command, string) {
+	c := Command{
+		Values: make([]int, 2),
+	}
+	for i := range inp {
+		switch inp[i] {
+		case 'm':
+			if _, err := fmt.Sscanf(inp[i:], "mul(%d,%d)", &c.Values[0], &c.Values[1]); err == nil {
+				c.Name = "mul"
+				return c, inp[i+len(c.String()):]
+			}
+		case 'd':
+			if strings.HasPrefix(inp[i:], "do()") {
+				c.Name = "do"
+				return c, strings.TrimPrefix(inp[i:], "do()")
+			} else if strings.HasPrefix(inp[i:], "don't()") {
+				c.Name = "don't"
+				return c, strings.TrimPrefix(inp[i:], "don't()")
+			}
+		}
+	}
+	return Command{}, ""
+}