part1 (3448B)
1--- Day 10: Monitoring Station --- 2 3You fly into the asteroid belt and reach the Ceres monitoring station. The Elves here have an 4emergency: they're having trouble tracking all of the asteroids and can't be sure they're safe. 5 6The Elves would like to build a new monitoring station in a nearby area of space; they hand you a 7map of all of the asteroids in that region (your puzzle input). 8 9The map indicates whether each position is empty (.) or contains an asteroid (#). The asteroids are 10much smaller than they appear on the map, and every asteroid is exactly in the center of its marked 11position. The asteroids can be described with X,Y coordinates where X is the distance from the left 12edge and Y is the distance from the top edge (so the top-left corner is 0,0 and the position 13immediately to its right is 1,0). 14 15Your job is to figure out which asteroid would be the best place to build a [1m[97mnew monitoring 16station[0m. A monitoring station can [1m[97mdetect[0m any asteroid to which it has [1m[97mdirect line of sight[0m - that 17is, there cannot be another asteroid [1m[97mexactly[0m between them. This line of sight can be at any angle, 18not just lines aligned to the grid or diagonally. The [1m[97mbest[0m location is the asteroid that can 19[1m[97mdetect[0m the largest number of other asteroids. 20 21For example, consider the following map: 22 23.#..# 24..... 25##### 26....# 27...[1m[97m#[0m# 28 29The best location for a new monitoring station on this map is the highlighted asteroid at 3,4 30because it can detect 8 asteroids, more than any other location. (The only asteroid it cannot detect 31is the one at 1,0; its view of this asteroid is blocked by the asteroid at 2,2.) All other asteroids 32are worse locations; they can detect 7 or fewer other asteroids. Here is the number of other 33asteroids a monitoring station on each asteroid could detect: 34 35.7..7 36..... 3767775 38....7 39...87 40 41Here is an asteroid (#) and some examples of the ways its line of sight might be blocked. If there 42were another asteroid at the location of a capital letter, the locations marked with the 43corresponding lowercase letter would be blocked and could not be detected: 44 45#......... 46...A...... 47...B..a... 48.EDCG....a 49..F.c.b... 50.....c.... 51..efd.c.gb 52.......c.. 53....f...c. 54...e..d..c 55 56Here are some larger examples: 57 58 59 - Best is 5,8 with 33 other asteroids detected: 60 61......#.#. 62#..#.#.... 63..#######. 64.#.#.###.. 65.#..#..... 66..#....#.# 67#..#....#. 68.##.#..### 69##...[1m[97m#[0m..#. 70.#....#### 71 72 73 - Best is 1,2 with 35 other asteroids detected: 74 75#.#...#.#. 76.###....#. 77.[1m[97m#[0m....#... 78##.#.#.#.# 79....#.#.#. 80.##..###.# 81..#...##.. 82..##....## 83......#... 84.####.###. 85 86 87 - Best is 6,3 with 41 other asteroids detected: 88 89.#..#..### 90####.###.# 91....###.#. 92..###.[1m[97m#[0m#.# 93##.##.#.#. 94....###..# 95..#.#..#.# 96#..#.#.### 97.##...##.# 98.....#.#.. 99 100 101 - Best is 11,13 with 210 other asteroids detected: 102 103.#..##.###...####### 104##.############..##. 105.#.######.########.# 106.###.#######.####.#. 107#####.##.#.##.###.## 108..#####..#.######### 109#################### 110#.####....###.#.#.## 111##.################# 112#####.##.###..####.. 113..######..##.####### 114####.##.####...##..# 115.#####..#.######.### 116##...#.####[1m[97m#[0m#####... 117#.##########.####### 118.####.#.###.###.#.## 119....##.##.###..##### 120.#.#.###########.### 121#.#.#.#####.####.### 122###.##.####.##.#..## 123 124 125 126Find the best location for a new monitoring station. [1m[97mHow many other asteroids can be detected from 127that location?[0m 128 129