AoC 2024 day 10 part 1

aoc2024/src/day10/python/solution.py

@@ -0,0 +1,57 @@
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+from typing import Sequence
+
+type Pos = tuple[int, int]
+
+_TRAILHEAD = 0
+_SUMMIT = 9
+_IS_GRADUAL_SLOPE = lambda level, next_level: next_level == level + 1
+
+
+def _find_trailheads(topographic_map: Sequence[str]) -> tuple[Pos, ...]:
+  """Finds the positions of trailheads. A trailhead is represented by '0'."""
+  trailhead_positions = []
+  for y in range(len(topographic_map)):
+    for x in range(len(topographic_map[0])):
+      if int(topographic_map[y][x]) == _TRAILHEAD:
+        trailhead_positions.append((y, x))
+  return tuple(trailhead_positions)
+
+
+def _count_reachable_summits(topo_map: Sequence[str], curr_pos: Pos, visited: set[Pos], num_summits: list[int]):
+  curr_level = int(topo_map[curr_pos[0]][curr_pos[1]])
+  if curr_level == _SUMMIT and curr_pos not in visited:
+    num_summits[0] += 1
+    visited.add(curr_pos)
+    return
+  visited.add(curr_pos)
+  for step in ((-1, 0), (0, 1), (1, 0), (0, -1)):
+    next_pos = (curr_pos[0] + step[0]), (curr_pos[1] + step[1])
+    within_map = 0 <= next_pos[0] < len(topo_map) and 0 <= next_pos[1] < len(topo_map[0])
+    if next_pos not in visited and within_map:
+      next_level = int(topo_map[next_pos[0]][next_pos[1]])
+      if _IS_GRADUAL_SLOPE(curr_level, next_level):
+        _count_reachable_summits(topo_map, next_pos, visited, num_summits)
+
+
+def get_score_sum(topographic_map: Sequence[str]) -> int:
+  """Gets the sum of all the trails from all the trailheads."""
+  sum_scores = 0
+  trailheads_positions: tuple[Pos, ...] = _find_trailheads(topographic_map)
+  for trailhead_pos in trailheads_positions:
+    num_summits = [0]  # Pass by reference.
+    _count_reachable_summits(topographic_map, trailhead_pos, set(), num_summits)
+    sum_scores += num_summits[0]
+  return sum_scores

aoc2024/test/day10/python/example1.txt

@@ -0,0 +1,7 @@
+1110111
+1111111
+1112111
+6543456
+7111117
+8111118
+9111119

aoc2024/test/day10/python/example2.txt

@@ -0,0 +1,7 @@
+1190119
+1111198
+1112117
+6543456
+7651987
+8761111
+9871111

aoc2024/test/day10/python/example3.txt

@@ -0,0 +1,7 @@
+1011911
+2111811
+3111711
+4567654
+1118113
+1119112
+1111101

aoc2024/test/day10/python/example4.txt

@@ -0,0 +1,8 @@
+89010123
+78121874
+87430965
+96549874
+45678903
+32019012
+01329801
+10456732

aoc2024/test/day10/python/input.txt

@@ -0,0 +1,55 @@
+3431014564567889856765432104561217856787834345650410767
+4321023673078974323896901223650306945698981298701321898
+5891134982100165010187878910765445034567820543432456734
+6780147890121016978776965010896532121054210612549345321
+5491056787630967869987654123987034910123341701678763430
+2312349896549890154890123234569123871431259898569321541
+1009456785656743213765012234678034565430968367878490651
+3238543876871056902153212105765123470121875454965581740
+0147612987962347810042309876894325989430960323784670891
+1254101796651258923031498121256716788567871212693021892
+2760189845640769854120567010343805697634543000542136763
+9871456732239878765987632129452934314523652101239545654
+8102320121148543651456783478761043203410789654318767650
+9810112510098652100347894567898110112341898769101658941
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+8941201872330178787145654324310569789076543654789301256
+2300312360545689656014345678210655690343218945689430987
+1412543451986770145123212109198744521256707650176521230
+0503694012876871234338905410012633230569876543287810321
+7654789323905965129847654321710123145678107434496929454
+8969876454914456056789878930891231010103298921345218765
+9878705967823327643056767011765310121012367800234309454
+3210214877012018034145654322654301234189456012125498723
+4569823898901219123233458743543210945676788321054321610
+2378778767432301012012769658652101876501699490167600501
+1267129876541018723103818569785438987612588588998010432
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+5487603478987034563365412323456410076345321761541454143
+6034512987656189879450343015667567125256780890132969056
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+9812340321201236903498985434543209852101234569834954301
+6701054450120145812385890365434901769015101078015867232
+5432365965034566703456581270125892378754098129126798103
+1019879870103875410787610789816765498763137430934567874
+2988218789212980325692101296700012187212346501887656985
+3678305654310341236543062345341123098703256232796540176
+4549456789423467877879871056732014567890107145601230234
+0032966761294558906978787810847812346921298050129821965
+1121879850387643216785696921956909855430386765434745874
+2340960345465434105898585430341098760987438876125636434
+3651451276576123434703450121252387721236589980030127123
+8960301289789016521012445696761456872345670891234898034
+7871210348058907897654332781890018965645671432105677645
+6210143232167812898101221650170123454534982145694789876
+4301250143456103763218760521985439210122173036783296765
+5654367897876554654109654432676098341013054921042107654
+8769016788985467891010123354342187657894567832030078503
+9878323412832345672561034565223476678743698948121899812
+6765467803421232983478743470110569569652107819238987601
+5653456912980221012989856789029678454765432108747896542
+1012321233470110103456765891098763243854549654656505632
+2187410345561256714987654302187654132923458743215014701
+7896509876456349876878963213456565001210567898304323892

aoc2024/test/day10/python/test_solution.py

@@ -0,0 +1,41 @@
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+import unittest
+
+from common.python3.AdventOfCodeTestCase import AdventOfCodeTestCase
+from aoc2024.src.day10.python.solution import get_score_sum
+
+
+class TestDay09Solution(AdventOfCodeTestCase):
+  def __init__(self, *args, **kwargs):
+    (super(TestDay09Solution, self).__init__(__file__, *args, **kwargs))
+
+  def test_part1_withExample_getsScore(self):
+    self.assertEqual(2, get_score_sum(self.examples[0]))
+
+  def test_part1_withExample2_getsScore(self):
+    self.assertEqual(4, get_score_sum(self.examples[1]))
+
+  def test_part1_withExample3_getsScore(self):
+    self.assertEqual(3, get_score_sum(self.examples[2]))
+
+  def test_part1_withExample4_getsScore(self):
+    self.assertEqual(36, get_score_sum(self.examples[3]))
+
+  def test_part1_withPuzzleInput_getsScore(self):
+    self.assertEqual(825, get_score_sum(self.input))
+
+
+if __name__ == '__main__':
+  unittest.main()