Mercurial > hg > aoc

comparison 2017/day03/problem @ 34:049fb8e56025

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Add problem statements and inputs
author Jordi Gutiérrez Hermoso <jordigh@octave.org>
date Tue, 09 Jan 2018 21:51:44 -0500
parents
children
comparison
equal deleted inserted replaced
33:bc652fa0a645 34:049fb8e56025
1 --- Day 3: Spiral Memory ---
2
3 You come across an experimental new kind of memory stored on an
4 infinite two-dimensional grid.
5
6 Each square on the grid is allocated in a spiral pattern starting at a
7 location marked 1 and then counting up while spiraling outward. For
8 example, the first few squares are allocated like this:
9
10 17 16 15 14 13
11 18 5 4 3 12
12 19 6 1 2 11
13 20 7 8 9 10
14 21 22 23---> ...
15
16 While this is very space-efficient (no squares are skipped), requested
17 data must be carried back to square 1 (the location of the only access
18 port for this memory system) by programs that can only move up, down,
19 left, or right. They always take the shortest path: the Manhattan
20 Distance between the location of the data and square 1.
21
22 For example:
23
24 Data from square 1 is carried 0 steps, since it's at the access port.
25
26 Data from square 12 is carried 3 steps, such as: down, left, left.
27
28 Data from square 23 is carried only 2 steps: up twice.
29
30 Data from square 1024 must be carried 31 steps.
31
32 How many steps are required to carry the data from the square
33 identified in your puzzle input all the way to the access port?
34
35 Your puzzle answer was 371.
36
37 --- Part Two ---
38
39 As a stress test on the system, the programs here clear the grid and
40 then store the value 1 in square 1. Then, in the same allocation order
41 as shown above, they store the sum of the values in all adjacent
42 squares, including diagonals.
43
44 So, the first few squares' values are chosen as follows:
45
46 Square 1 starts with the value 1.
47
48 Square 2 has only one adjacent filled square (with value 1), so it
49 also stores 1.
50
51 Square 3 has both of the above squares as neighbors and stores the
52 sum of their values, 2.
53
54 Square 4 has all three of the aforementioned squares as neighbors
55 and stores the sum of their values, 4.
56
57 Square 5 only has the first and fourth squares as neighbors, so it
58 gets the value 5.
59
60
61 Once a square is written, its value does not change. Therefore, the
62 first few squares would receive the following values:
63
64 147 142 133 122 59
65 304 5 4 2 57
66 330 10 1 1 54
67 351 11 23 25 26
68 362 747 806---> ...
69
70 What is the first value written that is larger than your puzzle input?
71
72 Your puzzle answer was 369601.
73
74 Both parts of this puzzle are complete! They provide two gold stars: **