2020-05: Binary Boarding

library(stringr)
library(DescTools)

df <- read.csv("input.csv")

Part 1

df$rowbin <- df$X1
df$rowbin <- str_replace_all(df$rowbin, "F", "0")
df$rowbin <- str_replace_all(df$rowbin, "B", "1")
df$rownum <- BinToDec(df$rowbin)

df$colbin <- df$X2
df$colbin <- str_replace_all(df$colbin, "L", "0")
df$colbin <- str_replace_all(df$colbin, "R", "1")
df$colnum <- BinToDec(df$colbin)

df$seatid <- (df$rownum * 8) + df$colnum
max(df$seatid)

[1] 828

write.csv(df, "input2.csv")

Part 2

df <- df[order(df$seatid),]

for(i in 804:1) {
  if(df$seatid[i + 1] - df$seatid[i] != 1) {
    myseat <- df$seatid[i + 1] - 1
    break
  }
}

myseat

[1] 565