AdventOfCode2k16/d09/d09.go

package main

import "strconv"
import "strings"
import "bufio"
import "fmt"
import "io"
import "os"

var (
    ex1 = true
)

type Compressed struct {
    BSize int
    Count int
}

func ReadCompressed(line string) *Compressed {
    if (line[len(line) -1] != ')') {
        return nil
    }
    line = line[0:len(line)-1]
    parts := strings.Split(line, "x")
    if (len(parts) != 2) {
        return nil
    }
    this := new(Compressed)
    var err error
    this.BSize, err = strconv.Atoi(parts[0])
    if (err != nil) {
        return nil
    }
    this.Count, err = strconv.Atoi(parts[1])
    if (err != nil) {
        return nil
    }
    return this
}

func readString(reader io.Reader, sep byte) (string, error) {
    buf := ""

    for {
        byteBuffer := make([]byte, 1)
        n, err := reader.Read(byteBuffer)
        buf += string(byteBuffer[:n])
        if (byteBuffer[0] == sep || err != nil) {
            return buf, err
        }
    }
    return "", nil
}

func doRead(reader io.Reader) int {
    length := 0
    for {
        line, err := readString(reader, '(')
        if (len(line) > 0 && line[len(line) -1] == '(') {
            length += len(line) -1

            line, err = readString(reader, ')')
            compressed := ReadCompressed(line)
            if (compressed == nil) {
                length += len(line)

            } else {
                var num int
                var buf string
                read := 0

                for ; compressed.BSize > read; {
                    bytes := make([]byte, compressed.BSize - read)

                    num, err = reader.Read(bytes)
                    read += num
                    if (!ex1) {
                        buf += string(bytes[:num])
                    }
                }

                if (ex1) {
                    length += read * compressed.Count
                } else {
                    length += doRead(strings.NewReader(buf)) * compressed.Count
                }
            }
        } else {
            length += len(line)

        }

        if err != nil {
            break
        }
    }
    return length
}

func main() {
    reader := bufio.NewReader(os.Stdin)
    length := doRead(reader)

    fmt.Println(length -1)
}