Day 5: Supply Stacks

day_05.R

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+library(dplyr, warn.conflicts = F)
+library(readr)
+library(tibble)
+library(stringr)
+library(tidyr)
+
+source("helpers/aoc.R")
+df <- read_lines(get_aoc("2022", "05"))
+
+# test data ---------------------------------------------------------------
+test <- list( t =
+"    [D]    
+[N] [C]    
+[Z] [M] [P]
+ 1   2   3 
+
+move 1 from 2 to 1
+move 3 from 1 to 3
+move 2 from 2 to 1
+move 1 from 1 to 2", 
+a1 = "CMZ", 
+a2 = "MCD")
+
+df_ <- read_lines(test$t)
+
+# -------------------------------------------------------------------------
+get_cols <- function(lines_){
+  s <- which.max(lines_ == "") - 1
+  strsplit(trimws(lines_[s]), "\\s+") |> unlist() |> as.integer() |> max()
+}
+get_cols(df_)
+
+
+get_state <- function(lines_){
+  s <- which.max(lines_ == "") - 2
+  read_fwf(paste(head(lines_,s),collapse = "\n"), fwf_widths(rep(4,get_cols(lines_)))) 
+}
+get_state(df_)
+#> # A tibble: 3 × 3
+#>   X1    X2    X3   
+#>   <chr> <chr> <chr>
+#> 1 <NA>  [D]   <NA> 
+#> 2 [N]   [C]   <NA> 
+#> 3 [Z]   [M]   [P]
+
+
+get_instr <- function(lines_){
+  s <- length(lines_) - which.max(lines_ == "")
+  tail(lines_,s) %>% 
+    # remove empty line
+    .[. != ""] %>% 
+    str_replace_all("(from|to)", ";") %>% 
+    str_remove_all("[^0-9;]") %>% 
+    enframe() %>% 
+    separate(value, into = c("n", "from", "to"), convert = T) %>% 
+    select(n,from,to)
+}
+get_instr(df_)
+#> # A tibble: 4 × 3
+#>       n  from    to
+#>   <int> <int> <int>
+#> 1     1     2     1
+#> 2     3     1     3
+#> 3     2     2     1
+#> 4     1     1     2
+
+
+# part 1 ------------------------------------------------------------------
+part_1 <- function(d = df){
+  state <- get_state(d) %>% as.matrix()
+
+  # flip the matrx and add some convas to pile those crates
+  # max matrix size 
+  state <- rbind(
+    state[nrow(state):1,],
+    matrix(rep(NA, nrow(state) * (ncol(state) - 1)  * ncol(state)), ncol = ncol(state))
+  )
+
+
+  instr <- get_instr(d) %>% setNames(c("n", "from", "to"))
+  instr <- instr[rep(1:nrow(instr),instr$n),c("from", "to")] %>% as.matrix()
+
+  for (i in 1:nrow(instr)){
+    from <- c(NA,instr[i,"from"])
+    from[1] <- which.max(is.na(state[,from[2]])) - 1 
+
+    to <- c(NA,instr[i,"to"])
+    to[1] <- which.max(is.na(state[,to[2]]))
+
+    state[to[1],to[2]] <- state[from[1],from[2]]
+    state[from[1],from[2]] <- NA
+  }
+  paste0(apply(state,2, \(x) rev(x[!is.na(x)])[1]), collapse = "") %>% str_remove_all("\\W")  
+}
+
+# part 2 ------------------------------------------------------------------
+part_2 <- function(d = df){
+  state <- get_state(d) %>% as.matrix()
+  state <- rbind(
+    state[nrow(state):1,],
+    matrix(rep(NA, nrow(state) * (ncol(state) - 1)  * ncol(state)), ncol = ncol(state))
+  )
+
+  instr <- get_instr(d) %>% setNames(c("n", "from", "to")) %>% as.matrix()
+
+  for (i in 1:nrow(instr)){
+    from_col <- instr[i,"from"]
+    from_rows <- which.max(is.na(state[,from_col])) - 1
+    from_rows <- (from_rows - instr[i,"n"] + 1):from_rows # [1] 1 2 3
+
+    to_col <- instr[i,"to"]
+    to_rows <- which.max(is.na(state[,to_col]))
+    to_rows <- to_rows:(to_rows + instr[i,"n"] - 1)
+
+    state[to_rows,to_col] <- state[from_rows,from_col]
+    state[from_rows,from_col] <- NA
+    # print(state[1:20,])
+  }
+  paste0(apply(state,2, \(x) rev(x[!is.na(x)])[1]), collapse = "") %>% str_remove_all("\\W")
+}
+
+# test --------------------------------------------------------------------
+testthat::test_that("AOC", {
+  df_ <- read_lines(test$t)
+  # testthat::expect_equal(f1_(df_$X1, df_$X2),test$p1)
+  # testthat::expect_equal(f2_(df_$X1, df_$X2),test$p2)
+
+  testthat::expect_equal(part_1(df_),test$a1)
+  testthat::expect_equal(part_2(!!df_),!!(test$a2))
+})
+
+# -------------------------------------------------------------------------
+part_1()
+part_2()
+
+
+