07: Camel Cards

library(mistlecode)

options(scipen = 999)

dt <-
  readLines('input.txt') |>
  stringr::str_split(' ') |>
  unlist() |>
  matrix(ncol = 2, byrow = TRUE) |>
  `colnames<-`(c('cards', 'bet')) |>
  tibble::as_tibble()

Part 1

This wasn’t too bad, but I originally used a dplyr::case_when instead of my if...else chain and because dplyr::case_when is vectorized, that wouldn’t work. However, when I swapped to my if...else chain, I accidentally marked three of a kind as the same value as a full house. Quite annoying, but an easy fix.

rank <- c('A', 'K', 'Q', 'J', 'T', 9:2) |> rev()
dt |>
  dplyr::mutate(
    '.nest' = purrr::map(.data$cards, \(x) {
      # x <- 'QJJQ2'
      h <-
        x |>
        stringr::str_split_1('') |>
        table() |>
        sort(decreasing = TRUE)
      hand <-
        if (length(h) == 1 && all(h %in% 5)) 7
        else if (length(h) == 2 && all(h %in% c(4, 1))) 6
        else if (length(h) == 2 && all(h %in% c(3, 2))) 5
        else if (length(h) == 3 && max(h) == 3) 4
        else if (length(h[h == 2]) == 2 && max(h) == 2) 3
        else if (length(h[h == 2]) == 1 && max(h) == 2) 2
        else 1
      high <-
        x |> 
        stringr::str_split_1('') |>
        purrr::map_int(\(y) which(rank == y)) |>
        stringr::str_pad(2, pad = '0') |>
        paste0(collapse = '') |>
        as.integer()
      list('hand' = hand, 'high' = high)
    })
  ) |>
  tidyr::unnest_wider('.nest') |>
  dplyr::arrange(.data$hand, .data$high) |>
  dplyr::mutate('bid' = as.integer(.data$bet) * dplyr::row_number()) |>
  dplyr::pull(.data$bid) |>
  sum()

[1] 250120186

Part 2

This took longer than it should’ve. I had the concept down quick, but was assigning the Joker to the highest available card rather than the card with the most occurrences. This is quickly apparent with the example KTJJT which with my original method would’ve become KTKKT, a full house, instead of KTTTT, four of a kind.

rank <- c('A', 'K', 'Q', 'T', 9:2, 'J') |> rev()
dt |>
  dplyr::mutate(
    '.nest' = purrr::map(.data$cards, \(x) {
      # x <- 'KTJJT'
      x <- stringr::str_split_1(x, '')
      h <-
        x |>
        table() |>
        sort(decreasing = TRUE)
      if (any(names(h) == 'J') & !all(names(h) == 'J')) {
        r <- which(rank == names(h[names(h) != 'J'])[1])
        h[rank[r]] <- h[rank[r]] + h['J']
      } else if (length(h) == 1 & all(names(h) == 'J')) {
        h <- c('A' = 5)
      }
      h <- h[names(h) != 'J']
      hand <- {
        if (length(h) == 1 && all(h %in% 5)) 7
        else if (length(h) == 2 && all(h %in% c(4, 1))) 6
        else if (length(h) == 2 && all(h %in% c(3, 2))) 5
        else if (length(h) == 3 && max(h) == 3) 4
        else if (length(h[h == 2]) == 2 && max(h) == 2) 3
        else if (length(h[h == 2]) == 1 && max(h) == 2) 2
        else 1
      }
      high <-
        x |> 
        purrr::map_int(\(y) which(rank == y)) |>
        stringr::str_pad(2, pad = '0') |>
        paste0(collapse = '') |>
        as.integer()
      list('hand' = hand, 'high' = high)
    })
  ) |>
  tidyr::unnest_wider('.nest') |>
  dplyr::arrange(.data$hand, .data$high) |>
  dplyr::mutate('bid' = as.integer(.data$bet) * dplyr::row_number()) |>
  dplyr::pull(.data$bid) |>
  sum()

[1] 250665248