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package main
import (
"bufio"
"fmt"
"log"
"os"
"regexp"
"strconv"
)
type cpu struct {
register int
cycle int
signalLog []int
}
func (c *cpu) instruction(op string, arg []string) {
addx := func(arg []string) {
x, err := strconv.Atoi(arg[0])
if err != nil {
log.Fatal("Got invalid arg to addx", err)
}
c.signalLog = append(c.signalLog, (c.cycle+1)*c.register, (c.cycle+2)*c.register)
c.register += x
c.cycle += 2
}
noop := func(arg []string) {
c.signalLog = append(c.signalLog, (c.cycle+1)*c.register)
c.cycle += 1
}
switch op {
case "addx":
addx(arg)
case "noop":
noop(arg)
default:
log.Fatal("Got unexpected input")
}
}
func NewCpu() *cpu {
return &cpu{
register: 1,
cycle: 0,
signalLog: []int(nil),
}
}
func main() {
f, err := os.Open("day10.txt")
if err != nil {
log.Fatal("could open input file", err)
}
// Part 1: Keep a logahead of signals
cpu := NewCpu()
s := bufio.NewScanner(f)
for s.Scan() {
r := regexp.MustCompile(`(?P<instruction>\w+) ?(?P<arg>[-0-9 ]+)?`)
m := r.FindStringSubmatch(s.Text())
switch words := len(m[1:]); words {
case 0:
log.Fatal("Got unexpected input")
case 1:
cpu.instruction(m[1], []string(nil))
default:
cpu.instruction(m[1], m[2:])
}
}
runningSum := 0
for _, c := range []int{20, 60, 100, 140, 180, 220} {
signal := cpu.signalLog[c-1]
fmt.Println(fmt.Sprintf("cycle %d:", c), signal)
runningSum += signal
}
fmt.Println("Part 1:", runningSum)
// Part 2: Scan the signal log
spri, te := 0, 2
for cycle, signal := range cpu.signalLog {
spri, te = (signal/(cycle+1))-1, (signal/(cycle+1))+1
c := cycle % 40
if spri <= c && c <= te {
cpu.signalLog[cycle] = 1
} else {
cpu.signalLog[cycle] = 0
}
}
for i := 0; i < len(cpu.signalLog); i += 40 {
for _, visi := range cpu.signalLog[i : i+40] {
if visi == 1 {
fmt.Print("#")
} else {
fmt.Print(".")
}
}
fmt.Println()
}
}
|
