2025 advent of code day 3

day_3.R

# first star
input <- read.fwf("input.txt", widths = rep(1L, 100L))

find_joltage <- function(x) {
  joltage <- ifelse(which.max(x) == length(x), as.integer(paste0(max(x[1:length(x) - 1]), max(x))),
                    as.integer(paste0(max(x), max(x[(which.max(x) + 1):length(x)]))))
  return(joltage)
  }

sum(apply(input, 1, find_joltage))

# second star
# take the highest possible joltage each time so long as there's enough numbers remaining to the right
find_more_joltage <- function(x, batteries = 12){
    battery <- max(x[1:(length(x) - (batteries - 1))])
    idx <- which.max(x[1:(length(x) - (batteries - 1))])
    if (batteries != 0) {
      return(10^(batteries - 1)*battery + find_more_joltage(x[-(1:idx)], (batteries - 1)))
    }
    else {
      return(0)
    }
  }

format(sum(apply(input, 1, find_more_joltage)), scientific = FALSE)