63 lines
2.6 KiB
Lua
63 lines
2.6 KiB
Lua
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-- What we've learn:
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-- - [x] Open a file as read (same signature as python's open(<file>[, mode]))
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-- - [x] Read file line-by-line
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-- - [x] Lua's iterator can be a generator function
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-- - [x] string -> number with tonumber()
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-- - [x] Syntactic sugar on collection length (or any that implements :len()): #<var>
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-- - [x] `print(..args)`; printing a nil yields an empty space. print also formats as a fancy table
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-- ```
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-- > print(1,2,3,4)
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-- 1 2 3 4
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-- > print(100, 200, 300, 400)
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-- 100 200 300 400
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-- ```
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-- - [x] CLI arguments are globally `arg`. arg[0] is the location of script, arg[1] is the first cli arg
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-- - [x] There is no loop-`continue` in Lua
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local function main(file_loc)
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counter = 0
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for group in io.lines(file_loc) do
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if #group > 0 then -- a better way is to strip the string first, idk how to do this, though
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-- despite the fact that we establish the token consists of digits
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-- Lua parses the token as "string" type.
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time_matches = group:gmatch("%d+")
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l_begin = tonumber(time_matches())
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l_end = tonumber(time_matches())
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r_begin = tonumber(time_matches())
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r_end = tonumber(time_matches())
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-- check if one elf's time is contained within the other
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-- 4 9 10 97
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if (l_begin <= r_begin and r_end <= l_end) or
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(r_begin <= l_begin and l_end <= r_end) then
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counter = counter + 1
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end
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end
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end
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print("part 1 " .. counter) -- print("part 1", counter) works as well. Guess it's var-args
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counter = 0
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for group in io.lines(file_loc) do
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if #group > 0 then -- a better way is to strip the string first, idk how to do this, though
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time_matches = group:gmatch("%d+")
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l_begin = tonumber(time_matches())
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l_end = tonumber(time_matches())
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r_begin = tonumber(time_matches())
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r_end = tonumber(time_matches())
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-- check if one elf's time is contained within the other
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if (l_begin >= r_begin and l_begin <= r_end) or -- l_begin within r's range
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(r_begin >= l_begin and r_begin <= l_end) or -- r_begin within l's range
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(l_end >= r_begin and l_end <= r_end) or -- l_end within r's range
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(r_end >= l_begin and r_end <= l_end) -- r_end within l's range
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then
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counter = counter + 1
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end
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end
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end
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print("part 2 " .. counter)
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end
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main(arg[1])
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