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Advent of Code 2021 in Lua

Solutions for adventOfCode In lua (ps-It's my first time working with lua, so feel free to point out any bad practices.)

Explanation

• DAY#3
  • Part1- For part one, n (where n is equal to the length of the digit) nested table within the table col is created, this contains the values of respective columns like so 0100, 0111, -> {0, 0}, {1, 1}, {0, 1}, {0, 1} in the real case, 12 such columns will be created. then we just loop through ever table, count the occurences of 0 or 1, add them to a central value, then decide the binary digit based on which one of the values are bigger (for the epsilion, its the opposite). we then convert these binaries to decimals, and multiply them together.
  • Part2- For part two, we have a function called getNofBin which takes in a table, and a position as a requirements, it then returns the quantity of zeros and one in the given position, and which one is greater. In the first function we repeat the loop until we are left where the getNofBin returns nil which says that the numbers are equal, in which case, we get the number with 1 in getOxyGen and 0 in getCo2Gen. In the second function, for getCo2Gen we invert the values, so greater = 0 -> greater = 1 and vice versa.
• DAY#4
  • Part1- This solution involved a lot of cutting and chopping. So to find the solution, first the given data was lexed in to indexable tables, so 1,0,1,1,2,3 -> {{1, 0, 1}, {1, 2, 3}} It is important to now, that the numerical values were attatched as a table {val=1, marked=false} this is done to check the winning board. the we have two helper functions checkCol and checkRow, both of which take in a block, and a position, and return true or false based on the marked value of the numbers (so true would mean that all numbers in a row or col were marked, thus marking our winner) in simBingo We loop through all the draws and the blocks, we pass the block through checkCol or checkRow, which if returns true, we end the function there and return the block, and the draw before the current draw, else we just loop through all the num values, and if they match the draw value, we "mark" them by setting marked = true.
  • Part2- I suspect there might be a better solution to do this, but what I ended up implementing was a function winningBlockIndex which is a modified version of simBingo and return the index of the block which one. We then have a for loop which extends till #blocks-1 (total number of blocks minus 1, so 2 in sample.txt), removing the block with the winningBlockIndex, so finally we are left with a table with just a single block, which we can say for sure, is the last winning one.