advent_day_10.go

// http://adventofcode.com/day/10
// run with "./advent_day_10 input iterations"
// e.g. ./advent_day_10 1113122113 40

package main

import "fmt"
import "os"
import "strconv"

func main() {
  input := os.Args[1]
  iterations, _ := strconv.Atoi(os.Args[2])

  for i := 1; i <= iterations; i++ {
    fmt.Printf("%d ", i)

    new_input    := ""
    run          := 1
    last         := input[0]
    input_length := len(input)

    for j := 1; j <= input_length; j++ {
      if j < input_length && input[j] == last {
        run += 1
      } else {
        new_input += strconv.Itoa(run) + string(last)

        if j < input_length {
          last = input[j]
          run = 1
        }
      }
    }
    input = new_input
  }

  fmt.Printf("\n%d\n", len(input))
}