1+ import static com .github .pareronia .aoc .Utils .last ;
2+
3+ import java .util .ArrayDeque ;
4+ import java .util .ArrayList ;
5+ import java .util .Deque ;
6+ import java .util .List ;
7+
8+ import com .github .pareronia .aoc .Grid .Cell ;
9+ import com .github .pareronia .aoc .IntGrid ;
10+ import com .github .pareronia .aoc .solution .Sample ;
11+ import com .github .pareronia .aoc .solution .Samples ;
12+ import com .github .pareronia .aoc .solution .SolutionBase ;
13+
14+ public final class AoC2024_10 extends SolutionBase <IntGrid , Integer , Integer > {
15+
16+ private AoC2024_10 (final boolean debug ) {
17+ super (debug );
18+ }
19+
20+ public static AoC2024_10 create () {
21+ return new AoC2024_10 (false );
22+ }
23+
24+ public static AoC2024_10 createDebug () {
25+ return new AoC2024_10 (true );
26+ }
27+
28+ @ Override
29+ protected IntGrid parseInput (final List <String > inputs ) {
30+ return IntGrid .from (inputs );
31+ }
32+
33+ private List <List <Cell >> getTrails (final IntGrid grid ) {
34+ class BFS {
35+ private final List <List <Cell >> trails = new ArrayList <>();
36+
37+ void bfs (final List <Cell > trail ) {
38+ final Deque <List <Cell >> q = new ArrayDeque <>(List .of (trail ));
39+ while (!q .isEmpty ()) {
40+ final List <Cell > curr = q .pop ();
41+ if (curr .size () == 10 ) {
42+ trails .add (curr );
43+ continue ;
44+ }
45+ final int next = grid .getValue (last (curr )) + 1 ;
46+ grid .getCapitalNeighbours (last (curr ))
47+ .filter (n -> grid .getValue (n ) == next )
48+ .forEach (n -> {
49+ final List <Cell > newTrail = new ArrayList <>(curr );
50+ newTrail .add (n );
51+ q .add (newTrail );
52+ });
53+ }
54+ }
55+ }
56+
57+ final BFS bfs = new BFS ();
58+ grid .getAllEqualTo (0 ).forEach (zero -> bfs .bfs (List .of (zero )));
59+ return bfs .trails ;
60+ }
61+
62+ @ Override
63+ public Integer solvePart1 (final IntGrid grid ) {
64+ final List <List <Cell >> trails = getTrails (grid );
65+ return trails .stream ()
66+ .map (trail -> trail .get (0 ))
67+ .distinct ()
68+ .mapToInt (zero -> (int ) trails .stream ()
69+ .filter (trail -> trail .get (0 ).equals (zero ))
70+ .map (trail -> trail .get (9 ))
71+ .distinct ()
72+ .count ())
73+ .sum ();
74+ }
75+
76+ @ Override
77+ public Integer solvePart2 (final IntGrid grid ) {
78+ return getTrails (grid ).size ();
79+ }
80+
81+ @ Override
82+ @ Samples ({
83+ @ Sample (method = "part1" , input = TEST , expected = "36" ),
84+ @ Sample (method = "part2" , input = TEST , expected = "81" ),
85+ })
86+ public void samples () {
87+ }
88+
89+ public static void main (final String [] args ) throws Exception {
90+ AoC2024_10 .create ().run ();
91+ }
92+
93+ private static final String TEST = """
94+ 89010123
95+ 78121874
96+ 87430965
97+ 96549874
98+ 45678903
99+ 32019012
100+ 01329801
101+ 10456732
102+ """ ;
103+ }
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