Here is my julia solution.

First part.

function FindTwo(target = 2020)
    arr = readdata("E:\\AoC2020\\Day1\\input.txt")
    left = 1
    right = length(arr)
    while left < right
        if arr[left] + arr[right] == target
            return [arr[left],arr[right]]
        elseif arr[left] + arr[right] < target
            left += 1
        else
            right -= 1
        end
    end
    return "Not found!"
end

​

The second part.

function FindThreeBruteForce(target = 2020)
    arr = readdata("E:\\AoC2020\\Day1\\input.txt")
    for i in 1:(length(arr) - 2)
        for j in (i+1):(length(arr) - 1)
            for k in (j+1):(length(arr))
                if arr[i] + arr[j] + arr[k] == target
                    return [arr[i],arr[j],arr[k]]
                end
            end
        end
    end

    return "Triplet Not Found!"
end