feat: day 10 completed

2024/inputs/day10.txt

@@ -0,0 +1,45 @@
+101234653436698943210876543298108967890123211
+900945762567787651028945054167211876965254300
+812876851008632112987632167054340105874367891
+743987945219541003456542108981233234567809892
+657641434349898764565876232190543456452912763
+898530125896701651698965945087612387301103454
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+012336765410589121470125960140340184678321670
+987449870323431034561076054057653296501234521
+876558901210120345665780143968934187410345438
+034569821025001256676891232877065056309654589
+125678438136789867589872301986174145218789678
+678776569245234798434565432765289036785890541
+589989478910135652329806567874376123896781030
+431276321210023101210715432990145678765432121
+120345290923412302345620121087230109650187656
+098010187874503210989430101256521212341090347
+187623456365694567876543232344560301032181298
+012510589456787655469854741023478912345672107
+143421674307897846988767858910890109852109856
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+140347123900389034502340191269854307894585014
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+123427890167654432106310345889299870122185432
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+894563454671410010987345665456987346787652450
+763674589582323225676298767645459855898101067
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+654327654654323601234569124349078321190187632
+789210125345434512103678765678767456783276543

2024/inputs/tests/test_day10.txt

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

2024/python/src/grice_py_aoc_2024/day10/main.py

@@ -1,22 +1,101 @@
 from __future__ import annotations
 
 import time
+from functools import cache
+from itertools import product
 from pathlib import Path
 
 DIR = Path(__file__).parent
 FILE = DIR.parents[3] / "inputs" / f"{DIR.stem}.txt"
 
+TRAILHEAD = "0"
+END_OF_TRAIL = "9"
 
-def part1(contents: str):
-    return "Not done yet!"
 
+def num_trails(contents: list[str], x: int, y: int, unique: bool = False) -> int:
+    @cache
+    def _find_all_trail_ends(x: int, y: int) -> set[tuple[int, int]]:
+        nonlocal contents
+        curr = contents[x][y]
+        if curr == END_OF_TRAIL:
+            return {(x, y)}
 
-def part2(contents: str):
-    return "Not done yet!"
+        target = str(int(curr) + 1)
+        trailheads = set()
+        for dx, dy in [
+            [-1, 0],
+            [0, 1],
+            [1, 0],
+            [0, -1],
+        ]:
+            newx, newy = x + dx, y + dy
+            if not 0 <= newx < len(contents) or not 0 <= newy < len(contents[0]):
+                # new point is outside bounds of the contents, ignore
+                continue
+            if contents[newx][newy] == target:
+                trailheads |= _find_all_trail_ends(x=newx, y=newy)
+        return trailheads
+
+    @cache
+    def _find_num_unique_trails(x: int, y: int) -> int:
+        # Oddly enough, this was the way I initially tried to solve Part 1
+        # due to my misunderstanding things. I had to then go back and return a set
+        # of those trail end coordinates, so as to have a unique set of trail ends,
+        # which I could then count with len.
+        # After finding that Part 2 was, indeed, this version,
+        # I just re-built what I did at first and re-implemented with a flag.
+        nonlocal contents
+        curr = contents[x][y]
+        if curr == END_OF_TRAIL:
+            return 1
+
+        target = str(int(curr) + 1)
+        trails = 0
+        for dx, dy in [
+            [-1, 0],
+            [0, 1],
+            [1, 0],
+            [0, -1],
+        ]:
+            newx, newy = x + dx, y + dy
+            if not 0 <= newx < len(contents) or not 0 <= newy < len(contents[0]):
+                # new point is outside bounds of the contents, ignore
+                continue
+            if contents[newx][newy] == target:
+                trails += _find_num_unique_trails(x=newx, y=newy)
+        return trails
+
+    if unique:
+        # Part 2
+        return _find_num_unique_trails(x=x, y=y)
+
+    # Part 1
+    trailhead_set = _find_all_trail_ends(x=x, y=y)
+    return len(trailhead_set)
+
+
+def part1(contents: list[str]) -> int:
+    total = 0
+    for x, line in enumerate(contents):
+        for y, char in enumerate(line):
+            if char == TRAILHEAD:
+                num = num_trails(contents=contents, x=x, y=y)
+                total += num
+    return total
+
+
+def part2(contents: list[str]) -> int:
+    total = 0
+    for x, line in enumerate(contents):
+        for y, char in enumerate(line):
+            if char == TRAILHEAD:
+                num = num_trails(contents=contents, x=x, y=y, unique=True)
+                total += num
+    return total
 
 
 def main():
-    contents = FILE.read_text()
+    contents = FILE.read_text().strip().split("\n")
 
     _start1 = time.perf_counter()
     result1 = part1(contents)

2024/python/src/grice_py_aoc_2024/day10/test_day10.py

@@ -8,18 +8,17 @@
 
 DIR = Path(__file__).parent
 TEST_FILE = DIR.parents[3] / "inputs/tests" / f"test_{DIR.stem}.txt"
-EXPECTED_PART_1 = "REPLACE ME!"
-EXPECTED_PART_2 = "REPLACE ME!"
+EXPECTED_PART_1 = 36
+EXPECTED_PART_2 = 81
 
 
 def test_part1():
-    contents = TEST_FILE.read_text()
+    contents = TEST_FILE.read_text().strip().split("\n")
     result = part1(contents)
     assert result == EXPECTED_PART_1
 
 
-@pytest.mark.xfail(reason=f"{DIR.stem} P1 incomplete")
 def test_part2():
-    contents = TEST_FILE.read_text()
+    contents = TEST_FILE.read_text().strip().split("\n")
     result = part2(contents)
     assert result == EXPECTED_PART_2