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