01: Not Quite Lisp

library(stringr)

dt <- readLines("input.txt")

Warning in readLines("input.txt"): incomplete final line found on 'input.txt'

Part 1

str_count(dt, "\\(") - str_count(dt, "\\)")

[1] 138

Part 2

dt <- data.frame("paren" = t(str_split_fixed(dt, "", nchar(dt))))
dt$val <- ifelse(dt$paren == "(", 1, -1)
which(cumsum(dt$val) == -1)[1]

[1] 1771