ursulams

# day 5 2025
# first star
options(scipen = 999)
input <- lapply(strsplit(readLines("input.txt"), "-"), as.numeric)
fresh_ranges <- Filter(function(x) {length(x) == 2}, input)
ids <- Filter(function(x) {length(x) == 1}, input)

length(unique(unlist(mapply(function(id, range){which(id >= range[1] & id <= range[2])}, list(ids), fresh_ranges))))

# second star

ursulams

# day 4 2025
# first star
input <- do.call(rbind, strsplit(readLines("input.txt"),""))

# calculate distances from each matrix cell to all others
# extract each cell's neighboring values for each element- max distance is one
indices <- which(input == input, arr.ind = TRUE)
d <- apply(as.matrix(dist(indices, "maximum", diag = TRUE)), 1, function(i) input[i == 1]) 
names(d) <- input
d <- d[grep("@", names(d))] 

ursulams

# 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))

ursulams

input <- sapply(read.csv("input.txt", header = FALSE), strsplit, "-")
input <- lapply(input, function(x){as.character(x[1]:x[2])})

get_invalids <- function(x, new = FALSE){
  ranges <- sapply(x, function(x){subset(x, nchar(x) %% 2  == 0)}) # repeating numbers are of even length
  invalids <- sapply(ranges, function(x) {as.numeric(grep("^(\\d+)\\1$", x, value = TRUE))})
  if (new == TRUE){
    invalids <- sapply(x, function(i) {as.numeric(grep("^(\\d+)(\\1)+$", i, value = TRUE))})
  }
  return(invalids)

ursulams

# first star
# swap out l/r for operators
input <- apply(read.table("input.txt", header = FALSE), 1, 
               function(x) gsub("L", "-", gsub("R", "+", x)))

input <- sapply(input, function(x) eval(parse(text = x)))

start <- 50

clicks <- cumsum(c(start,input))

ursulams

# first star
input <- readLines("input.txt")

bigints <- sapply(strsplit(input, "\\:"), as.numeric)[1,]
ints <-  sapply(strsplit(input, " "), as.numeric)
ints <- lapply(ints, function(x) x[!is.na(x)])

reductor <- function(i){
  result <- Reduce(function(x, y)  c(x * y, x + y), i)
  return(result)

ursulams

# first star
input <- as.matrix(read.fwf("input.txt", widths = rep(1, 130), comment.char = ""))

# pad to indicate exit
#input <- rbind("E", cbind("E", input, "E"), "E") 

starting <- as.vector(which(input == "^", arr.ind = TRUE)[1,])

# function moves n,m position in matrix
step <- function(direction, mode){

ursulams

# first star
input <- readLines("input.txt")

pages <- as.data.frame(t(sapply(strsplit(input[grep("\\|", input)], "\\|"), as.integer)))
updates <- lapply(strsplit(input[grep(",", input)], ","), as.integer)


get_order <- function(u){
  ordered <- pages[(pages$V1 %in% u) & (pages$V2 %in% u), ] # which page pairs apply to update
  ordered$V1_idx <- sapply(ordered$V1, function(x){which(u == x)}) # get indices

ursulams

# first star
input <- as.matrix(read.fwf("input.txt", widths = rep(1, 140)))

finder <- function(x) {x <- paste(x, collapse = "")
  lengths(regmatches(x, gregexpr("XMAS", x))) +
  lengths(regmatches(x, gregexpr("SAMX", x)))
}

# tally horizontal & vertical matches
h_finds <- apply(input, 1, finder)

ursulams

# first star
input <- paste0(readLines("input.txt"), collapse = " ") # ingest as one big blob
expression <- "mul\\([0-9]+,[0-9]+\\)"

# returns parsed string with generic function to allow for string to expression conversion
renamer <- function(x){
  str2lang(gsub("mul", "prod", regmatches(x, gregexpr(expression, x))))
}

multipliers <- renamer(input)