Day 2: Rock Paper Scissors

day_02.R

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+library(dplyr)
+library(readr)
+
+source("helpers/aoc.R")
+df <- read_table(get_aoc("2022", "02"), col_names = F)
+
+# test data ---------------------------------------------------------------
+test <- list( t =
+"A Y
+B X
+C Z", p1 = c(8, 1, 6),
+      p2 = c("X", "X", "X"),
+      a1 = 15, 
+      a2 = 12)
+
+
+# part 1 ------------------------------------------------------------------
+# A for Rock, B for Paper, and C for Scissors
+# X for Rock, Y for Paper, and Z for Scissors
+# Your total score is the sum of your scores for each round. The score 
+# for a single round is the score for the shape you selected 
+# (1 for Rock, 2 for Paper, and 3 for Scissors) plus the score for the outcome 
+# of the round (0 if you lost, 3 if the round was a draw, and 6 if you won).
+
+score <- function(oponent_moves, my_moves){
+  m_score <- matrix( c(4, 8, 3, 
+                       1, 5, 9, 
+                       7, 2, 6), 
+                     nrow = 3, 
+                     byrow = T, 
+                     dimnames = list(oponent = c("A", "B", "C"), me = c("X","Y","Z")))
+  m_score[cbind(oponent_moves, my_moves)]
+}
+
+part_1 <- function(d = df){
+  sum(score(d[[1]], d[[2]]))
+}
+
+
+
+
+# part 2 ------------------------------------------------------------------
+move <- function(oponent_moves, my_round_results){
+  # Anyway, the second column says how the round needs to end: 
+  # X means you need to lose, 
+  # Y means you need to end the round in a draw, and 
+  # Z means you need to win.
+
+  #                     Lose Draw Win
+  #                     X(R) Y(P) Z(S)
+  m_move  <- matrix( c("Z", "X", "Y", # A - rock
+                       "X", "Y", "Z", # B - paper
+                       "Y", "Z", "X"),# C - scissors
+                     nrow = 3, 
+                     byrow = T, 
+                     dimnames = list(oponent = c("A", "B", "C"), me = c("X","Y","Z")))
+  m_move[cbind(oponent_moves, my_round_results)]
+}
+
+part_2 <- function(d = df){
+  d$move <- move(d[[1]], d[[2]])
+  sum(score(d[[1]],d$move))
+}
+
+
+# test --------------------------------------------------------------------
+testthat::test_that("AOC Day 2", {
+  df_ <- read_table(test$t, col_names = F)
+  testthat::expect_equal(score(df_$X1, df_$X2),test$p1)
+  testthat::expect_equal(move(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()
+
+
+