August 13, 2018

## Advent of Code 2015 Day 4 - The Ideal Stocking Stuffer

Santa needs help mining some AdventCoins (very similar to bitcoins) to use as gifts for all the economically forward-thinking little girls and boys.

To do this, he needs to find MD5 hashes which, in hexadecimal, start with at least **five zeroes**. The input to the MD5 hash is some secret key (your puzzle input, given below) followed by a number in decimal. To mine AdventCoins, you must find Santa the lowest positive number (no leading zeroes: `1`

, `2`

, `3`

, ...) that produces such a hash.

For example:

- If your secret key is
`abcdef`

, the answer is`609043`

, because the MD5 hash of`abcdef609043`

starts with five zeroes (`000001dbbfa...`

), and it is the lowest such number to do so. - If your secret key is
`pqrstuv`

, the lowest number it combines with to make an MD5 hash starting with five zeroes is`1048970`

; that is, the MD5 hash of`pqrstuv1048970`

looks like`000006136ef...`

.

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## Part Two

Now find one that starts with **six zeroes**.

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