Add problems for days 1-7

2020/day06/problem

@@ -0,0 +1,129 @@
+# Advent of Code
+
+--- Day 6: Custom Customs ---
+
+   As your flight approaches the regional airport where you'll switch to a much larger plane,
+   customs declaration forms are distributed to the passengers.
+
+   The form asks a series of 26 yes-or-no questions marked a through z. All you need to do is
+   identify the questions for which anyone in your group answers "yes". Since your group is
+   just you, this doesn't take very long.
+
+   However, the person sitting next to you seems to be experiencing a language barrier and
+   asks if you can help. For each of the people in their group, you write down the questions
+   for which they answer "yes", one per line. For example:
+
+ abcx
+ abcy
+ abcz
+
+   In this group, there are 6 questions to which anyone answered "yes": a, b, c, x, y, and z.
+   (Duplicate answers to the same question don't count extra; each question counts at most
+   once.)
+
+   Another group asks for your help, then another, and eventually you've collected answers
+   from every group on the plane (your puzzle input). Each group's answers are separated by a
+   blank line, and within each group, each person's answers are on a single line. For example:
+
+ abc
+
+ a
+ b
+ c
+
+ ab
+ ac
+
+ a
+ a
+ a
+ a
+
+ b
+
+   This list represents answers from five groups:
+
+     • The first group contains one person who answered "yes" to 3 questions: a, b, and c.
+     • The second group contains three people; combined, they answered "yes" to 3 questions:
+       a, b, and c.
+     • The third group contains two people; combined, they answered "yes" to 3 questions: a,
+       b, and c.
+     • The fourth group contains four people; combined, they answered "yes" to only 1
+       question, a.
+     • The last group contains one person who answered "yes" to only 1 question, b.
+
+   In this example, the sum of these counts is 3 + 3 + 3 + 1 + 1 = 11.
+
+   For each group, count the number of questions to which anyone answered "yes". What is the
+   sum of those counts?
+
+   Your puzzle answer was 6763.
+
+--- Part Two ---
+
+   As you finish the last group's customs declaration, you notice that you misread one word in
+   the instructions:
+
+   You don't need to identify the questions to which anyone answered "yes"; you need to
+   identify the questions to which everyone answered "yes"!
+
+   Using the same example as above:
+
+ abc
+
+ a
+ b
+ c
+
+ ab
+ ac
+
+ a
+ a
+ a
+ a
+
+ b
+
+   This list represents answers from five groups:
+
+     • In the first group, everyone (all 1 person) answered "yes" to 3 questions: a, b, and c.
+     • In the second group, there is no question to which everyone answered "yes".
+     • In the third group, everyone answered yes to only 1 question, a. Since some people did
+       not answer "yes" to b or c, they don't count.
+     • In the fourth group, everyone answered yes to only 1 question, a.
+     • In the fifth group, everyone (all 1 person) answered "yes" to 1 question, b.
+
+   In this example, the sum of these counts is 3 + 0 + 1 + 1 + 1 = 6.
+
+   For each group, count the number of questions to which everyone answered "yes". What is the
+   sum of those counts?
+
+   Your puzzle answer was 3512.
+
+   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
+
+   Visible links
+   . https://adventofcode.com/
+   . https://adventofcode.com/2020/about
+   . https://adventofcode.com/2020/events
+   . https://adventofcode.com/2020/settings
+   . https://adventofcode.com/2020/auth/logout
+   . Advent of Code Supporter
+	https://adventofcode.com/2020/support
+   . https://adventofcode.com/2020
+   . https://adventofcode.com/2020
+   . https://adventofcode.com/2020/support
+   . https://adventofcode.com/2020/sponsors
+   . https://adventofcode.com/2020/leaderboard
+   . https://adventofcode.com/2020/stats
+   . https://adventofcode.com/2020/sponsors
+   . https://en.wikipedia.org/wiki/Customs_declaration
+   . https://adventofcode.com/2020
+   . https://adventofcode.com/2020/day/6/input