2024

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— R Day 3 Part 1 —

#' Sum of multiplications
#'
#' Uses regex to find numbers in format mul(x, y). Multiplies each pair and
#' adds the results together.
#'
#' @param input
#' Character vector of lines to parse for numbers to multiply.
#'
#' @return
#' The sum of results of multiplications
solve_day3_part1 <- function(input) {
  muls <- stringi::stri_extract_all_regex(input,
                                          "(?<=mul\\()[0-9]+,[0-9]+(?=\\))")

  muls <- unlist(muls)
  muls <- strsplit(muls, ",")
  muls <- purrr::list_transpose(muls)
  muls <- lapply(muls, as.numeric)

  sum(muls[[1]] * muls[[2]])
}
Run
aoc_source(day = 3, part = 1)

input = aoc_read(day = 3)

aoc_run(solve_day3_part1(input))
Elapsed: 0.012 seconds
Memory:  1110 KB

— R Day 3 Part 2 —

#' Sum of enabled multiplications
#'
#' Add do() to the start of the input. Uses regex to split the input on do() and
#' don't(), removing all the sections that start with don't(). Then find the sum
#' of multiplying remaining pairs.
#'
#' @param input
#' Character vector of lines to parse for numbers to multiply.
#'
#' @return
#' The sum of results of enabled multiplications
solve_day3_part2 <- function(input) {
  line <- paste0(input, collapse = "")
  line <- paste0("do()", line)

  split <- stringi::stri_split_regex(line, "(?=do\\(\\))|(?=don't\\(\\))")
  split <- unlist(split)
  split <- split[substring(split, 1, 4) == "do()"]

  mul_sums <- lapply(split, sum_muls)

  sum(unlist(mul_sums))
}

#' Sum of multiplications
#'
#' Same as part 1 solution. Uses regex to find numbers in format mul(x, y).
#' Multiplies each pair and adds the results together.
#'
#' @param input
#' Character vector of lines to parse for numbers to multiply.
#'
#' @return
#' The sum of results of multiplications
sum_muls <- function(section) {
  muls <- stringi::stri_extract_all_regex(section,
                                          "(?<=mul\\()[0-9]+,[0-9]+(?=\\))")

  if (is.na(muls)) return(0)

  muls <- unlist(muls)
  muls <- strsplit(muls, ",")
  muls <- purrr::list_transpose(muls)
  muls <- lapply(muls, as.numeric)

  sum(muls[[1]] * muls[[2]])
}
Run
aoc_source(day = 3, part = 2)

input = aoc_read(day = 3)

aoc_run(solve_day3_part2(input))
Elapsed: 0.016 seconds
Memory:  142 KB

— Python Day 3 Part 1 —

import re

def solve_day3_part1(text):
  """
  Sum of multiplications
  
  Uses regex to find numbers in format mul(x, y). Multiplies each pair and
  adds the results together.
  
  Parameters
  ----------
  text : list of str
    Lines to parse for numbers to multiply.
      
  Returns
  -------
  int
    The sum of results of multiplications
  """
  muls = [re.findall("(?<=mul\()[0-9]+,[0-9]+(?=\))", line) for line in text]
  muls = [pair for line in muls for pair in line] 
  muls = [pair.split(",") for pair in muls]
  muls = [[int(num) for num in pair] for pair in muls]
  muls = [pair[0] * pair[1] for pair in muls]
  
  return(sum(muls))
Run
aoc_source(day = 3, part = 1)

input = aoc_read(day = 3)

result = aoc_run("solve_day3_part1(input)")
Elapsed: 0.005 seconds
Memory:  286 KB

— Python Day 3 Part 2 —

import re

def solve_day3_part2(text):
  """
  Sum of enabled multiplications
  
  Add do() to the start of the input. Uses regex to split the input on do() and
  don't(), removing all the sections that start with don't(). Then find the sum
  of multiplying remaining pairs.
  
  Parameters
  ----------
  text : list of str
    Lines to parse for numbers to multiply.
      
  Returns
  -------
  int
    The sum of results of enabled multiplications
  """
  line = "".join(text)
  line = "do()" + line
  
  splits = re.split("(?=do\(\))|(?=don't\(\))", line)
  splits = [line for line in splits if line[0:5] != "don't"]
  
  mul_sums = [sum_muls(line) for line in splits]
  
  return(sum(mul_sums))
  
def sum_muls(section):
  """
  Sum of multiplications
  
  Uses regex to find numbers in format mul(x, y). Multiplies each pair and
  adds the results together.
  
  Parameters
  ----------
  section : list of str
    Lines to parse for numbers to multiply.
      

  Returns
  -------
  int
    The sum of results of multiplications
  """
  muls = re.findall("(?<=mul\()[0-9]+,[0-9]+(?=\))", section)
  
  if len(muls) == 0:
    return(0)
  
  muls = [pair.split(",") for pair in muls]
  muls = [[int(num) for num in pair] for pair in muls]
  muls = [pair[0] * pair[1] for pair in muls]
  
  return(sum(muls))
Run
aoc_source(day = 3, part = 2)

input = aoc_read(day = 3)

result = aoc_run("solve_day3_part2(input)")
Elapsed: 0.004 seconds
Memory:  52 KB
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