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Advent Of Code 2022 - Day 25

· 2 min read
James Crawford
James Crawford
Jactl Creator

See Day 25 for a detailed description of the problem.

Continuing to solve the Advent of Code 2022 problems (see Advent of Code - Day 1).

Links:

To run the example code in this post save the code into file such as advent.jactl and take your input from the Advent of Code site (e.g. advent.txt) and run it like this:

$ cat advent.txt | java -jar jactl-{{ site.content.jactl_version }}.jar advent.jactl

This is the last challenge for Advent of Code 2022 and day 25 has only one part, unlike the other days.

A fairly simple challenge for the last day. The goal is to take a list of numbers encoded in a code they have called SNAFU, sum them, and then output the sum as a SNAFU number.

In SNAFU the numbers are base 5 but the twist is that the digits are =, -, 0, 1, 2 with = meaning -2 and - meaning -1. Decoding these numbers is pretty straightforward but encoding is a bit trickier.

In the end, not a lot of code for this challenge.

def n = stream(nextLine).map{ it.reduce(0L){ v,d -> v*5 + ['2':2,'1':1,'0':0,'-':-1,'=':-2][d] } }.sum()
for (def dval=0, value=''; ; n /= 5) {
  return value if n <= 0 && dval <= 2;
  dval = (n % 5) + (dval > 2 ? 1 : 0)
  value = '012=-'[dval % 5] + value
}