Advent Of Code 2021

Advent of Code 2021: https://adventofcode.com/2021

Day 1: Sonar Sweep

From a list of numbers (depths), count how many depths are greater than the previous depth.

199 (N/A - no previous measurement)
200 (increased)
208 (increased)
210 (increased)
200 (decreased)
207 (increased)
240 (increased)
269 (increased)
260 (decreased)
263 (increased)

Part 1:

Count how many increases in depth there are.

Part 2:

Take the sum of every three consecutive depths and then count the increases in the sums.

Day 2: Dive!

From a list of directions and amounts (course), calculate the depth and distance traveled.

forward 5
down 5
forward 8
up 3
down 8
forward 2

Part 1:

Calculate the product of the final depth and distance.

Part 2:

Calculate depth by using an aiming factor based on distance. Calculate the product of the final depth and distance.

Day 3: Binary Diagnostic

From a list of binary numbers, perform some operations to determine most common and least common bits at index. These are used to create two new binary numbers.

Part 1:

Construct a binary number based on the most common bit at index for each number in the list. Construct a binary number based on the least common bit at index for each number in the list. (opposite of previous number)

FInd the product of those two numbers.

Part 2:

This time you find the most common bit at index for a copy of the list of numbers, but remove any number that does not have that bit at that index. And the least common bit at index for a copy of the original list and remove any numbers that do not have that bit at that index.

Keep doing that for the modified list until one number remains.

Get the product of the two final numbers.

Day 4: Giant Squid

Play BINGO! From list of balls chosen, and a set of many bingo boards, find the bingo boards that are winners.

7,4,9,5,11,17,23,2,0,14,21,24,10,16,13,6,15,25,12,22,18,20,8,19,3,26,1

22 13 17 11  0
 8  2 23  4 24
21  9 14 16  7
 6 10  3 18  5
 1 12 20 15 19

 3 15  0  2 22
 9 18 13 17  5
19  8  7 25 23
20 11 10 24  4
14 21 16 12  6

14 21 17 24  4
10 16 15  9 19
18  8 23 26 20
22 11 13  6  5
 2  0 12  3  7

Part 1:

Find the first winning bingo board to beat the giant squid.

Part 2:

Find the last winning bingo board to insure the giant squid wins.

Day 5: Hydrothermal Venture

Given a set of line segments as two points, graph each line segment.

0,9 -> 5,9
8,0 -> 0,8
9,4 -> 3,4
2,2 -> 2,1
7,0 -> 7,4
6,4 -> 2,0
0,9 -> 2,9
3,4 -> 1,4
0,0 -> 8,8
5,5 -> 8,2

Part 1:

Graph each point the line segment covers. Find all areas that have at least 1 overlap. Only consider horizontal and vertical lines.

Part 2:

Graph each point the line segment covers. Find all areas that have at least 1 overlap. Consider horizontal, vertical lines and diagnoanl lines..

Day 6: Lanternfish

Fish everywhere. Given a set of data: a list of numbers, each number represents how long until the fish reproduces. A fish reproduces once every 7 days. New born fish take 8 days for their first offspring. Find the number of fish after n days.

Initial state: 3,4,3,1,2
After  1 day:  2,3,2,0,1
After  2 days: 1,2,1,6,0,8
After  3 days: 0,1,0,5,6,7,8
After  4 days: 6,0,6,4,5,6,7,8,8
After  5 days: 5,6,5,3,4,5,6,7,7,8
After  6 days: 4,5,4,2,3,4,5,6,6,7
After  7 days: 3,4,3,1,2,3,4,5,5,6
After  8 days: 2,3,2,0,1,2,3,4,4,5
After  9 days: 1,2,1,6,0,1,2,3,3,4,8
After 10 days: 0,1,0,5,6,0,1,2,2,3,7,8
After 11 days: 6,0,6,4,5,6,0,1,1,2,6,7,8,8,8
After 12 days: 5,6,5,3,4,5,6,0,0,1,5,6,7,7,7,8,8
After 13 days: 4,5,4,2,3,4,5,6,6,0,4,5,6,6,6,7,7,8,8
After 14 days: 3,4,3,1,2,3,4,5,5,6,3,4,5,5,5,6,6,7,7,8
After 15 days: 2,3,2,0,1,2,3,4,4,5,2,3,4,4,4,5,5,6,6,7
After 16 days: 1,2,1,6,0,1,2,3,3,4,1,2,3,3,3,4,4,5,5,6,8
After 17 days: 0,1,0,5,6,0,1,2,2,3,0,1,2,2,2,3,3,4,4,5,7,8
After 18 days: 6,0,6,4,5,6,0,1,1,2,6,0,1,1,1,2,2,3,3,4,6,7,8,8,8,8

Part 1:

Part 1 description

Part 2:

Part 2 description

Day 10: Syntax Scoring

Overall description

Part 1:

Part 1 description

Part 2:

Part 2 description

Part 2 description

glasstoestudio / adventofcode_2021 Goto Github PK