Advent of Code 2023 is nigh

Post by masklinn » Fri, Dec 01, 2023, 7:08 PM UTC

greymalik wrote: post #52

I've never done AoC before. It seems like the success criteria is primarily about getting the correct answer, and secondarily about submitting a solution as quickly as possible if you want to be on the leaderboard. Is that right? Is there any centralized place for seeing other people's solutions? I'd like to be able to learn from how others approach the problem, and what more elegant or performant solutions exist tha…

Post by codr7 » Fri, Dec 01, 2023, 7:09 PM UTC

randomifcpfan wrote: post #47

zerr wrote: post #27

Earlier quoted context omitted.

Generally, such edge-cases usually make the solution ugly and the process unpleasant. The aim of such puzzles should be a pleasant process culminating with a beautiful solution.

The potential for overlapping numbers was the thing that tripped up many developers. But a simple “find the first number searching from each end, just like the puzzle instructions asked” implementation just worked. The lesson is to read the puzzle instructions carefully and avoid solving more general problems.

Post by Huppie » Fri, Dec 01, 2023, 7:11 PM UTC

torbencarstens wrote: post #138

shever73 wrote: post #92

As others have said, part 2 of today's was really difficult. I finally solved it using Python regex `overlapped=true`, but it was very tricky. The irritation of having all of the test cases passing, but it failing for my challenge input! I hope it doesn't scare off newcomers, but I already know a few who have given up on part 2.

Another option when using regex would be to use the lookahead[0] operator (as long as supported, which is the case for the python re module) (?=(one|two|three|[...])) would return `["two", "one"]` for the input string `twone` since the lookahead operator doesn't consume the next character. [0] https://www.regular-expressions.info/lookaround.html

Post by recursive » Fri, Dec 01, 2023, 7:12 PM UTC

abound wrote: post #183

hypersoar wrote: post #182

Earlier quoted context omitted.

I heard the question was difficult before solving it, and then I was surprised when I didn't hit any speed bumps. The overlapping case didn't even occur to me. It turns out I stumbled upon a simple solution: use two regexes. One to match the first digit, and one to match the last. Then the overlapping is a total non-issue.

If the whole numeric part of the string was something like "eightwo", I think that solution would fail.

Post by waterhouse » Fri, Dec 01, 2023, 7:13 PM UTC

criddell wrote: post #180

nick0garvey wrote: post #170

Earlier quoted context omitted.

I also started to write a finite state machine for part 2 but found it too tedious to craft by hand. How did you do it?

Not OP, but I too first thought of a state machine. As soon as I started to write it I realized I was over-solving a day-1 problem. So I switched to brute force https://pastebin.com/r1jNCSdm Once I get a line back from that, it's the same problem as part A.

  pbpaste | bash -c '
    tt=0
    while read x; do
      y=$(( 10 *
            $(echo $x |
              egrep -o "[0-9]|one|two|three|four|five|six|seven|eight|nine" |
              head -1 |
              sed -E "s/one/1/; s/two/2/; s/three/3/; s/four/4/; s/five/5/; s/six/6/; s/seven/7/; s/eight/8/; s/nine/9/")
          + $(echo $x |
              rev |
              egrep -o "[0-9]|eno|owt|eerht|ruof|evif|xis|neves|thgie|enin" |
              head -1 |
              rev |
              sed -E "s/one/1/; s/two/2/; s/three/3/; s/four/4/; s/five/5/; s/six/6/; s/seven/7/; s/eight/8/; s/nine/9/")))
      tt=$((tt+y))
    done
    echo $tt'