Christmas' Coding

How do people celebrate Christmas? The answer to this question may vary. There are some who don't. There are some who celebrate only the Christmas itself. And, there are people who celebrate it early, as early as the coming of September, so that they celebrate it in the months ended with -ber (September, October, November, December). Finally, there are also people who make certain preparation to make themselves worthy to welcome it. This preparation is what called the Advent Season.
Earlier this year, I found out about the Advent of Code, a website by Eric Wastl, dedicated to celebrate Christmas (or Advent) by posting puzzles. From 2015, every December, from the 1st to the 25th, there will be 25 puzzles, one for each day. Each puzzle consists of two parts, which will give those who can solve it two stars. Provided every part of the puzzles is solved, there will be 50 stars to be earned. But,  these are not ordinary puzzles. These are puzzles for programmers, coders, and hobbyist. To solve this puzzles, logical thinking, algorithmic problem solving, and some skill in coding are needed.
I am not a programmer or a coder, more a hobbyist. But, once I discovered about Advent of Code, I have been obsessed to solve all the puzzle, not in those popular programming language, such as C, JavaScript, Perl, Python, or PHP, but in Microsoft Excel. Not only that I am not familiar with those language (I can learn though), but I also considered this as a challenge. Besides, Microsoft Excel serves the purpose of solving those puzzle, although not as fast or easy as other programming language does. At first I convinced myself that all puzzles can be solved using only formulas, without needing any VBA codes. But, as I tried to solve more difficult ones, the more I realized that VBA is needed and even makes some calculations faster.
So, for the coming posts, I will write about this attempt, solving AoC problems in Excel, starting from 2015.