Solve both parts

Author: Paul2708

Day-18/python/paul2708/day18.py

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+import math
+from typing import Tuple
+
+import numpy as np
+from scipy.sparse import csr_matrix
+from scipy.sparse.csgraph import shortest_path
+from tqdm import tqdm
+
+from shared.paul2708.input_reader import *
+from shared.paul2708.output import write
+
+lines = read_plain_input(day=18)
+
+SIZE = 71
+
+memory = [(int(line.split(",")[0]), int(line.split(",")[1])) for line in lines]
+
+
+def position_to_vertex(position: Tuple[int, int]) -> int:
+    return (position[0] * SIZE) + position[1]
+
+
+def compute_shortest_path(amount_of_bytes: int) -> np.ndarray:
+    dim = SIZE * SIZE
+    adjacency_matrix = np.zeros((dim, dim))
+
+    for i in range(SIZE):
+        for j in range(SIZE):
+            for x, y in [(-1, 0), (1, 0), (0, 1), (0, -1)]:
+                if 0 <= i + x < SIZE and 0 <= j + y < SIZE and not (i + x, j + y) in memory[:amount_of_bytes]:
+                    adjacency_matrix[position_to_vertex((i, j))][position_to_vertex((i + x, j + y))] = 1
+
+    dist_matrix = shortest_path(csgraph=csr_matrix(adjacency_matrix), indices=0)
+    return dist_matrix[-1]
+
+
+# Part 1
+write(f"The shortest path after <1024 bytes> requires <{int(compute_shortest_path(1024))} steps>.")
+
+# Part 2
+lower = 1
+upper = len(memory) - 1
+index = (upper + lower) // 2
+
+with tqdm(total=math.ceil(math.log(len(memory), 2))) as progress_bar:
+    while not (compute_shortest_path(index - 1) != np.inf and compute_shortest_path(index) == np.inf):
+        if compute_shortest_path(index) != np.inf:
+            lower = index
+        else:
+            upper = index
+
+        index = (upper + lower) // 2
+
+        progress_bar.update(1)
+
+write(f"The byte <{memory[index - 1]}> destroys the path.")