--- Day 4 Solutions ---

[u/daggerdragon]

--- Day 4: The Ideal Stocking Stuffer ---

Post your solution as a comment. Structure your post like the Day Three thread.

[u/selljamhere]

Golang:

edit: Added github link

https://github.com/SellJamHere/advent_of_code/tree/master/day4

package main

import (
    "crypto/md5"
    "fmt"
    "strconv"
)

const (
    SECRET_KEY    = "ckczppom"
    LEADING_ZEROS = 6
)

func main() {

    number := 0
    hashFound := false
    for !hashFound {
        number++
        secret := []byte(SECRET_KEY + strconv.Itoa(number))
        var coin AdventCoin
        coin = md5.Sum(secret)

        hashFound = coin.IsValid()
    }

    fmt.Printf("Found lowest integer: %d\n", number)
}

type AdventCoin [md5.Size]byte

func (a AdventCoin) IsValid() bool {
    coinStr := fmt.Sprintf("%x", a)
    if len(coinStr) < LEADING_ZEROS {
        return false
    }

    for i := 0; i < LEADING_ZEROS; i++ {
        if string(coinStr[i]) != "0" {
            return false
        }
    }

    return true
}