Add problems for days 1-7

2020/day07/problem

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+# Advent of Code
+
+--- Day 7: Handy Haversacks ---
+
+   You land at the regional airport in time for your next flight. In fact, it looks like
+   you'll even have time to grab some food: all flights are currently delayed due to issues in
+   luggage processing.
+
+   Due to recent aviation regulations, many rules (your puzzle input) are being enforced about
+   bags and their contents; bags must be color-coded and must contain specific quantities of
+   other color-coded bags. Apparently, nobody responsible for these regulations considered how
+   long they would take to enforce!
+
+   For example, consider the following rules:
+
+ light red bags contain 1 bright white bag, 2 muted yellow bags.
+ dark orange bags contain 3 bright white bags, 4 muted yellow bags.
+ bright white bags contain 1 shiny gold bag.
+ muted yellow bags contain 2 shiny gold bags, 9 faded blue bags.
+ shiny gold bags contain 1 dark olive bag, 2 vibrant plum bags.
+ dark olive bags contain 3 faded blue bags, 4 dotted black bags.
+ vibrant plum bags contain 5 faded blue bags, 6 dotted black bags.
+ faded blue bags contain no other bags.
+ dotted black bags contain no other bags.
+
+   These rules specify the required contents for 9 bag types. In this example, every faded
+   blue bag is empty, every vibrant plum bag contains 11 bags (5 faded blue and 6 dotted
+   black), and so on.
+
+   You have a shiny gold bag. If you wanted to carry it in at least one other bag, how many
+   different bag colors would be valid for the outermost bag? (In other words: how many colors
+   can, eventually, contain at least one shiny gold bag?)
+
+   In the above rules, the following options would be available to you:
+
+     • A bright white bag, which can hold your shiny gold bag directly.
+     • A muted yellow bag, which can hold your shiny gold bag directly, plus some other bags.
+     • A dark orange bag, which can hold bright white and muted yellow bags, either of which
+       could then hold your shiny gold bag.
+     • A light red bag, which can hold bright white and muted yellow bags, either of which
+       could then hold your shiny gold bag.
+
+   So, in this example, the number of bag colors that can eventually contain at least one
+   shiny gold bag is 4.
+
+   How many bag colors can eventually contain at least one shiny gold bag? (The list of rules
+   is quite long; make sure you get all of it.)
+
+   Your puzzle answer was 302.
+
+   The first half of this puzzle is complete! It provides one gold star: *
+
+--- Part Two ---
+
+   It's getting pretty expensive to fly these days - not because of ticket prices, but because
+   of the ridiculous number of bags you need to buy!
+
+   Consider again your shiny gold bag and the rules from the above example:
+
+     • faded blue bags contain 0 other bags.
+     • dotted black bags contain 0 other bags.
+     • vibrant plum bags contain 11 other bags: 5 faded blue bags and 6 dotted black bags.
+     • dark olive bags contain 7 other bags: 3 faded blue bags and 4 dotted black bags.
+
+   So, a single shiny gold bag must contain 1 dark olive bag (and the 7 bags within it) plus 2
+   vibrant plum bags (and the 11 bags within each of those): 1 + 1*7 + 2 + 2*11 = 32 bags!
+
+   Of course, the actual rules have a small chance of going several levels deeper than this
+   example; be sure to count all of the bags, even if the nesting becomes topologically
+   impractical!
+
+   Here's another example:
+
+ shiny gold bags contain 2 dark red bags.
+ dark red bags contain 2 dark orange bags.
+ dark orange bags contain 2 dark yellow bags.
+ dark yellow bags contain 2 dark green bags.
+ dark green bags contain 2 dark blue bags.
+ dark blue bags contain 2 dark violet bags.
+ dark violet bags contain no other bags.
+
+   In this example, a single shiny gold bag must contain 126 other bags.
+
+   How many individual bags are required inside your single shiny gold bag?
+
+   Your puzzle answer was 4165.
+
+   Both parts of this puzzle are complete! They provide two gold stars: **
+
+   At this point, you should return to your Advent calendar and try another puzzle.
+
+   If you still want to see it, you can get your puzzle input.
+
+References
+
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+   . https://adventofcode.com/2020/day/7/input