Dijkstra algorithm with binary grid

.pre-commit-config.yaml

@@ -15,8 +15,8 @@ repos:
     hooks:
     -   id: auto-walrus
 
-  - repo: https://github.com/charliermarsh/ruff-pre-commit
-    rev: v0.0.272
+  - repo: https://github.com/astral-sh/ruff-pre-commit
+    rev: v0.0.274
     hooks:
       - id: ruff
 

data_structures/queue/double_ended_queue.py

@@ -32,7 +32,7 @@ class Deque:
         the number of nodes
     """
 
-    __slots__ = ["_front", "_back", "_len"]
+    __slots__ = ("_front", "_back", "_len")
 
     @dataclass
     class _Node:
@@ -54,7 +54,7 @@ class _Iterator:
             the current node of the iteration.
         """
 
-        __slots__ = ["_cur"]
+        __slots__ = "_cur"
 
         def __init__(self, cur: Deque._Node | None) -> None:
             self._cur = cur

graphs/dijkstra_binary_grid.py

@@ -0,0 +1,89 @@
+"""
+This script implements the Dijkstra algorithm on a binary grid.
+The grid consists of 0s and 1s, where 1 represents
+a walkable node and 0 represents an obstacle.
+The algorithm finds the shortest path from a start node to a destination node.
+Diagonal movement can be allowed or disallowed.
+"""
+
+from heapq import heappop, heappush
+
+import numpy as np
+
+
+def dijkstra(
+    grid: np.ndarray,
+    source: tuple[int, int],
+    destination: tuple[int, int],
+    allow_diagonal: bool,
+) -> tuple[float | int, list[tuple[int, int]]]:
+    """
+    Implements Dijkstra's algorithm on a binary grid.
+
+    Args:
+        grid (np.ndarray): A 2D numpy array representing the grid.
+        1 represents a walkable node and 0 represents an obstacle.
+        source (Tuple[int, int]): A tuple representing the start node.
+        destination (Tuple[int, int]): A tuple representing the
+        destination node.
+        allow_diagonal (bool): A boolean determining whether
+        diagonal movements are allowed.
+
+    Returns:
+        Tuple[Union[float, int], List[Tuple[int, int]]]:
+        The shortest distance from the start node to the destination node
+        and the shortest path as a list of nodes.
+
+    >>> dijkstra(np.array([[1, 1, 1], [0, 1, 0], [0, 1, 1]]), (0, 0), (2, 2), False)
+    (4.0, [(0, 0), (0, 1), (1, 1), (2, 1), (2, 2)])
+
+    >>> dijkstra(np.array([[1, 1, 1], [0, 1, 0], [0, 1, 1]]), (0, 0), (2, 2), True)
+    (2.0, [(0, 0), (1, 1), (2, 2)])
+
+    >>> dijkstra(np.array([[1, 1, 1], [0, 0, 1], [0, 1, 1]]), (0, 0), (2, 2), False)
+    (4.0, [(0, 0), (0, 1), (0, 2), (1, 2), (2, 2)])
+    """
+    rows, cols = grid.shape
+    dx = [-1, 1, 0, 0]
+    dy = [0, 0, -1, 1]
+    if allow_diagonal:
+        dx += [-1, -1, 1, 1]
+        dy += [-1, 1, -1, 1]
+
+    queue, visited = [(0, source)], set()
+    matrix = np.full((rows, cols), np.inf)
+    matrix[source] = 0
+    predecessors = np.empty((rows, cols), dtype=object)
+    predecessors[source] = None
+
+    while queue:
+        (dist, (x, y)) = heappop(queue)
+        if (x, y) in visited:
+            continue
+        visited.add((x, y))
+
+        if (x, y) == destination:
+            path = []
+            while (x, y) != source:
+                path.append((x, y))
+                x, y = predecessors[x, y]
+            path.append(source)  # add the source manually
+            path.reverse()
+            return matrix[destination], path
+
+        for i in range(len(dx)):
+            nx, ny = x + dx[i], y + dy[i]
+            if 0 <= nx < rows and 0 <= ny < cols:
+                next_node = grid[nx][ny]
+                if next_node == 1 and matrix[nx, ny] > dist + 1:
+                    heappush(queue, (dist + 1, (nx, ny)))
+                    matrix[nx, ny] = dist + 1
+                    predecessors[nx, ny] = (x, y)
+
+    return np.inf, []
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()

maths/least_common_multiple.py

@@ -67,7 +67,7 @@ def benchmark():
 
 
 class TestLeastCommonMultiple(unittest.TestCase):
-    test_inputs = [
+    test_inputs = (
         (10, 20),
         (13, 15),
         (4, 31),
@@ -77,8 +77,8 @@ class TestLeastCommonMultiple(unittest.TestCase):
         (12, 25),
         (10, 25),
         (6, 9),
-    ]
-    expected_results = [20, 195, 124, 210, 1462, 60, 300, 50, 18]
+    )
+    expected_results = (20, 195, 124, 210, 1462, 60, 300, 50, 18)
 
     def test_lcm_function(self):
         for i, (first_num, second_num) in enumerate(self.test_inputs):

project_euler/problem_054/sol1.py

@@ -47,30 +47,30 @@
 
 class PokerHand:
     """Create an object representing a Poker Hand based on an input of a
-    string which represents the best 5 card combination from the player's hand
+    string which represents the best 5-card combination from the player's hand
     and board cards.
 
     Attributes: (read-only)
-        hand: string representing the hand consisting of five cards
+        hand: a string representing the hand consisting of five cards
 
     Methods:
         compare_with(opponent): takes in player's hand (self) and
             opponent's hand (opponent) and compares both hands according to
             the rules of Texas Hold'em.
             Returns one of 3 strings (Win, Loss, Tie) based on whether
-            player's hand is better than opponent's hand.
+            player's hand is better than the opponent's hand.
 
         hand_name(): Returns a string made up of two parts: hand name
             and high card.
 
     Supported operators:
         Rich comparison operators: <, >, <=, >=, ==, !=
 
-    Supported builtin methods and functions:
+    Supported built-in methods and functions:
         list.sort(), sorted()
     """
 
-    _HAND_NAME = [
+    _HAND_NAME = (
         "High card",
         "One pair",
         "Two pairs",
@@ -81,10 +81,10 @@ class PokerHand:
         "Four of a kind",
         "Straight flush",
         "Royal flush",
-    ]
+    )
 
-    _CARD_NAME = [
-        "",  # placeholder as lists are zero indexed
+    _CARD_NAME = (
+        "",  # placeholder as tuples are zero-indexed
         "One",
         "Two",
         "Three",
@@ -99,7 +99,7 @@ class PokerHand:
         "Queen",
         "King",
         "Ace",
-    ]
+    )
 
     def __init__(self, hand: str) -> None:
         """

pyproject.toml

@@ -103,6 +103,7 @@ max-complexity = 17  # default: 10
 "machine_learning/linear_discriminant_analysis.py" = ["ARG005"]
 "machine_learning/sequential_minimum_optimization.py" = ["SIM115"]
 "matrix/sherman_morrison.py" = ["SIM103", "SIM114"]
+"other/l*u_cache.py" = ["RUF012"]
 "physics/newtons_second_law_of_motion.py" = ["BLE001"]
 "project_euler/problem_099/sol1.py" = ["SIM115"]
 "sorts/external_sort.py" = ["SIM115"]