AdventOfCode2k16/d05/d05.go

package main

import "encoding/hex"
import "crypto/md5"
import "strconv"
import "strings"
import "fmt"
import "os"

func string2Md5(input string, incr int) string {
    inputBytes := []byte(input + strconv.Itoa(incr))
    hashed := make([]byte, 16)

    for i, j := range(md5.Sum(inputBytes)) {
        hashed[i] = j
    }

    result := hex.EncodeToString(hashed)
    return result
}

func ex1(doorId string) string {
    var result string

    for i := 0 ; len(result) < 8; i++ {
        hashed := (string2Md5(doorId, i))
        if (strings.HasPrefix(hashed, "00000")) {
            result += string(hashed[5])

            fmt.Printf(result)
            for j := len(result); j < 8; j++ {
                fmt.Printf("_")
            }
            fmt.Printf("\n")
        }
    }
    return result
}

func isDone(in []rune) bool {
    res := len(in)

    for i := 0; i < len(in); i++ {
        if in[i] != 0 {
            res--;
        }
    }
    return res == 0
}

func ex2(doorId string) string {
    result := make([]rune, 8)

    for i := 0 ; true ; i++ {
        hashed := (string2Md5(doorId, i))
        if (strings.HasPrefix(hashed, "00000")) {
            if (hashed[5] <= '7') {
                if (result[hashed[5] - '0'] == 0) {
                    result[hashed[5] - '0'] = rune(hashed[6])
                    for j := 0; j < 8; j++ {
                        if result[j] == 0 {
                            fmt.Printf("_")
                        } else {
                            fmt.Printf("%c", result[j])
                        }
                    }
                    fmt.Printf("\n")
                    if isDone(result) {
                        return string(result)
                    }
                }
            }
        }
    }
    return ""
}

func main() {
    if len(os.Args) != 2 {
        fmt.Fprintln(os.Stderr, "Usage: PROG doorId")
    } else {
        doorId := os.Args[1]
        ex1(doorId)
    }
}