Reposted by Sarah Harris
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![#Day 6 - Trash Compactor - Part 1
#load the puzzle input, transpose it, and setup the sums and products across all numeric columns
D6P1 <- read.table("D6input.txt", sep = "" , header = F , na.strings ="", stringsAsFactors= F) |> t()
D6P1 <- data.frame(D6P1) |> rename(pm = ncol(D6P1)) |> mutate(across(starts_with("X"), as.numeric))
numeric_cols <- D6P1[sapply(D6P1, is.numeric)]
D6P1$numericcolssum <- rowSums(numeric_cols)
D6P1$numericcolsprod <- apply(numeric_cols, 1, prod)
D6P1 <- D6P1 |> mutate(correctresult = if_else(pm == "+",numericcolssum, numericcolsprod))
print(paste("answer is",sum(D6P1$correctresult)))](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:ni73qa4ccdu323lqbc5db53p/bafkreia6vvrhedgtrxmq5u6kubsr4qni27texdbvzudhjzuhlxorhhyjfi)
![#Part 2 - need to re-read in the data - the spaces matter now!
D6P2 <- data.frame(input = readLines("D6input.txt"), stringsAsFactors = FALSE)
char_matrix <- str_split_fixed(D6P2$input, "", n = nchar(D6P2$input[1])) |> t()
D6P2 <- as.data.frame(char_matrix) |> rename(pm = ncol(char_matrix)) |> mutate(across(starts_with("V"), as.numeric))
numeric_cols <- D6P2[sapply(D6P2, is.numeric)]
D6P2$numericcolssum <- rowSums(numeric_cols, na.rm = T)
D6P2 <- D6P2 |> filter(numericcolssum > 0) |>
mutate(across(starts_with("V"), as.character)) |>
mutate(across(starts_with("V"), ~ replace_na(.,""))) |>
mutate(newnum = as.numeric(do.call(paste0, across(starts_with("V"))))) |> #paste the chars back together in the right order
mutate(indexno = ifelse(pm != " ", 1, NA), indexno = cumsum(replace_na(indexno, 0))) |> #give each set of numbers a URN
mutate(pm = na_if(pm, " ")) |> fill(pm, .direction = "down") #fill in the plus/mult symbols in the blank bits
additions <- D6P2 |> filter(pm == "+") |> group_by(indexno) |> summarise(result = sum(newnum)) |> ungroup()
mults <- D6P2 |> filter(pm == "*") |> group_by(indexno) |> summarise(result = prod(newnum)) |> ungroup()
print(paste("answer is",sum(additions$result)+sum(mults$result)))](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:ni73qa4ccdu323lqbc5db53p/bafkreieblxtymfllmaohsa4ygy5wn7h7ndx5c62nufyhhslhjpie36vpfu)
![# Day 5 - Cafeteria - Part 1
inputD5P1 <- data.frame(input = readLines("D5input.txt"), stringsAsFactors = FALSE) #load data and split into 2 parts
blankrow <- which(inputD5P1$input == "")[1]
top <- inputD5P1 |> filter(row_number() < blankrow)
bottom <- inputD5P1 |> filter(row_number() > blankrow) |>
rename(candidate = 1) |> mutate(candidate = as.numeric(candidate)) |> arrange(candidate)
#split the top bit into from and to and tidy up the overlapping ranges:
top <- top |> separate(input, into = c("fromnum", "tonum"), sep = "-") |>
mutate(fromnum = as.numeric(fromnum), tonum = as.numeric(tonum)) |> arrange(fromnum)
tidied_top <- tidy_ranges(top) |> arrange(fromnum)
#get rid of deffo spoiled items
bottom <- bottom |> filter(candidate >= min(tidied_top$fromnum) & candidate <= max(tidied_top$tonum))
#now check through the ranges for each remaining candidate - find the first "from" that it is >= , and then mark as a match
# if <= the to on that row - then when we have passed the "to" on a row, get rid
freshcounter <- 0
for (i in 1:nrow(bottom)) {
candidate <- bottom[i,1]
tidied_top <- filter(tidied_top, tonum >= candidate)
matchrow <- which(tidied_top$fromnum <= candidate)[1]
if (!is.na(matchrow) && candidate <= tidied_top[matchrow,2]) {freshcounter <- freshcounter + 1}}
print(paste("answer is",freshcounter))](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:ni73qa4ccdu323lqbc5db53p/bafkreiffuaqq4xp773csjgpqc74b3ml23gtlxojrmd4xvskxkggdma53uq)
![# Day 4 - Printing Department - Part 1
D4mat <- do.call(rbind, strsplit(readLines("D4input.txt"), "")) #load the data into a matrix
matdim <- nrow(D4mat)
D4mat <- pad_matrix(D4mat)
# then just loop through every cell from [2,2] to [matdim+1,matdim+1] and count up the @s in all 8 directions
rollcount <- 0
for (i in 2:(matdim+1)) {
for (j in 2:(matdim+1)) {
if(D4mat[i,j] == "@") {
neighbours <- sum(D4mat[i-1,j-1] == "@",D4mat[i-1,j] == "@", D4mat[i-1,j+1] == "@",
D4mat[i,j-1] == "@", F, D4mat[i,j+1] == "@",
D4mat[i+1,j-1] == "@",D4mat[i+1,j] == "@", D4mat[i+1,j+1] == "@")
if(neighbours < 4) {rollcount <- rollcount + 1} }}}
print(paste("answer is",rollcount))](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:ni73qa4ccdu323lqbc5db53p/bafkreigcbuod6jyetf3hippqx6juqmgvgv2q6yelhdqqasizo2enexbsia)
![#Part 2 - use the same padded matrix that was set up in part 1
#instead of just counting the reachable rolls, this time count them and also replace with a dot to 'remove' them.
# keep passing through until no more rolls get removed.
rollcount <- 0
while (TRUE) {
removed <- 0
for (i in 2:(matdim+1)) {
for (j in 2:(matdim+1)) {
if(D4mat[i,j] == "@") {
neighbours <- sum(D4mat[i-1,j-1] == "@",D4mat[i-1,j] == "@", D4mat[i-1,j+1] == "@",
D4mat[i,j-1] == "@", F, D4mat[i,j+1] == "@",
D4mat[i+1,j-1] == "@",D4mat[i+1,j] == "@", D4mat[i+1,j+1] == "@")
if(neighbours < 4) {
rollcount <- rollcount + 1
removed <- removed + 1
D4mat[i,j] <- '.'}}}}
if (removed == 0) break }
print(paste("answer is",rollcount))](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:ni73qa4ccdu323lqbc5db53p/bafkreidtibycevy2huvgkfh45rk2kn6ddbj27bdne7sj7gyzbw2cvidxqm)
![#Day 3 - Lobby - Part 1
inputD3P1 <- data.frame(input = readLines("D3input.txt"), stringsAsFactors = FALSE)
inputD3P1 <- inputD3P1 |> rowwise() |>
mutate(shorter_input = str_sub(input, end = -2),
firstdigit = max(strsplit(shorter_input, "")[[1]]),
firstdigitpos = which(strsplit(shorter_input, "")[[1]] == firstdigit)[1],
remainder = str_sub(input, start = (firstdigitpos + 1)),
seconddigit = max(strsplit(remainder, "")[[1]]),
joltage = as.numeric(firstdigit)*10+as.numeric(seconddigit)) |> ungroup()
print(paste("answer is",sum(inputD3P1$joltage)))](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:ni73qa4ccdu323lqbc5db53p/bafkreiggilvxz4ucacciqdvez56gjo5d2e4p6ygqgnsjoyg7ohzqhvt2a4)
![#Part 2 - the same thing but twelve times instead of 2
inputD3P1 <- data.frame(input = readLines("D3input.txt"), stringsAsFactors = FALSE)
inputD3P1 <- inputD3P1 |> rowwise() |>
mutate(shorter_input = str_sub(input, end = -12),
firstdigit = max(strsplit(shorter_input, "")[[1]]),
firstdigitpos = which(strsplit(shorter_input, "")[[1]] == firstdigit)[1],
remainder = str_sub(input, start = (firstdigitpos + 1), end = -11),
seconddigit = max(strsplit(remainder, "")[[1]]),
seconddigitpos = which(strsplit(remainder, "")[[1]] == seconddigit)[1],
remainder2 = str_sub(input, start = (firstdigitpos+seconddigitpos + 1), end = - 10),
thirddigit = max(strsplit(remainder2, "")[[1]]),
thirddigitpos = which(strsplit(remainder2, "")[[1]] == thirddigit)[1],
remainder3 = str_sub(input, start = (firstdigitpos+seconddigitpos +thirddigitpos + 1), end = -9),
#and so on ......
joltage = as.numeric(firstdigit)*100000000000+as.numeric(seconddigit)*10000000000+
as.numeric(thirddigit)*1000000000+as.numeric(fourthdigit)*100000000+
as.numeric(fifthdigit)*10000000+as.numeric(sixthdigit)*1000000+
as.numeric(seventhdigit)*100000+as.numeric(eigthdigit)*10000+
as.numeric(ninthdigit)*1000+as.numeric(tenthdigit)*100+
as.numeric(eleventhdigit)*10+as.numeric(twelthdigit)) |> ungroup()
print(paste("answer is",sum(inputD3P1$joltage)))](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:ni73qa4ccdu323lqbc5db53p/bafkreieoiiutaoff43otqfp5vgbkbvwj2hfgkemdo24jwqticlwmg2sfu4)
![#Part 2 uses same input data frame already loaded in my part 1 solution
allpotentials <- data.frame(potentials = character())
for (i in 1:nrow(inputD2P1)) {
j <- as.numeric(inputD2P1[i,1])
k <- as.numeric(inputD2P1[i,2])
for (n in j:k) {
p <- as.character(n)
if (grepl("^(.+)\\1+$", p)) {allpotentials <- rbind(allpotentials,p) } } }
allpotentials <- allpotentials |> rename(potentials = 1) |> mutate(repeaters = as.numeric(potentials))
print(paste("answer is",sum(allpotentials$repeaters)))](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:ni73qa4ccdu323lqbc5db53p/bafkreiefiots5uf5hytqp3leassqjauur22otr6grdcwhl3x356p2womeu)
![#Day 2 "Gift Shop" - part 1
library(bit64) # need this as some of the numbers in the main input are large
inputD2P1 <- readLines("D2_input.txt")
inputD2P1 <- strsplit(inputD2P1, ",")[[1]] |>
lapply(function(x) as.integer64(strsplit(x, "-")[[1]])) |>
do.call(what = rbind) |>
as.data.frame()
options(scipen = 999)
is_even <- function(x) x %% 2 == 0
kounter <- 0
for (i in 1:nrow(inputD2P1)) {
x <- inputD2P1[i,1]
y <- inputD2P1[i,2]
z <- as.character(x)
startlen = str_length(z)
if(!is_even(startlen)) {
z <- as.character(10^startlen)
startlen <- startlen + 1 }
half <- substr(z,1,(startlen/2))
trial <- as.numeric(paste0(half,half))
while (TRUE) {
if (trial >= x & trial <= y) {kounter <- kounter + as.numeric(trial)}
if (trial <= y) {
half <- as.character(as.numeric(half) + 1)
trial <- as.numeric(paste0(half,half))
} else break }}
print(paste("answer is",kounter))](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:ni73qa4ccdu323lqbc5db53p/bafkreib2ij3xyb3g7aiqhg4molvvbuxvmopxtnqwjymd5tmjei7n3xwr5u)
