From 2671d317ff4104ec44b62e79db3700d3e38c4a9f Mon Sep 17 00:00:00 2001
From: Andrew Scott <git@acscott.dev>
Date: Tue, 30 Aug 2022 00:21:11 -0400
Subject: [PATCH] Added Puzzle.py

---
 Puzzle.py | 140 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 140 insertions(+)
 create mode 100644 Puzzle.py

diff --git a/Puzzle.py b/Puzzle.py
new file mode 100644
index 0000000..8a2bcdd
--- /dev/null
+++ b/Puzzle.py
@@ -0,0 +1,140 @@
+from typing import Deque
+
+
+def solve_puzzle(Board: list, Source: tuple, Destination: tuple):
+    """Finds a solution to a 2-D puzzle using a breadth first search
+
+    Parameters
+    ----------
+    Board : list
+        A graph represented as an adjacency matrix
+    Source : tuple
+        The starting point on the board
+    Destination : tuple
+        The goal position
+    """
+
+    queue = Deque()
+    queue.append(Source)
+    visited = {}
+
+    if is_valid(Source[0], Source[1], Board, visited):
+        visited[Source] = 0
+        if Source == Destination:
+            return [Destination]
+    else:
+        return None
+
+    while len(queue) > 0:
+        r, c = queue.popleft()
+        possible_moves = [(1, 0), (0, 1), (-1, 0), (0, -1)]
+        for move_row, move_col in possible_moves:
+            row, col = r + move_row, c + move_col
+            if is_valid(row, col, Board, visited):
+                queue.append((row, col))
+                visited[(row, col)] = visited[(r, c)] + 1
+                if (row, col) == Destination:
+                    return get_path(row, col, visited)
+
+    return None
+
+
+def is_valid(x: int, y: int, Board: list, visited: dict) -> bool:
+    """Helper for solve_puzzle() to determine if a move is valid
+
+    Parameters
+    ----------
+    x : int
+        Row
+    y : int
+        Column
+    Board : list
+        A graph represented as an adjacency matrix
+    visited : dict
+        Coordinates that have been visited
+
+    Returns
+    -------
+    bool
+        True if the move is valid, otherwise False
+    """
+
+    exists = False
+    valid = False
+
+    if (x >= 0 and y >= 0) and (x < len(Board) and y < len(Board[0])):
+        exists = True
+
+    target = (x, y)
+    if exists:
+        if Board[x][y] != "#" and target not in visited:
+            valid = True
+
+    return valid and exists
+
+
+def get_path(row: int, col: int, visited: dict) -> tuple:
+    """Helper for solve_puzzle() to assemble the steps and moves into lists
+
+    Parameters
+    ----------
+    row : int
+        Row on the board
+    col : int
+        Column on the board
+    visited : dict
+        Coordinates that have been visited
+
+    Returns
+    -------
+    tuple
+        List of tuples containing coordinates traversed, and list of directions
+    """
+
+    steps = visited[(row, col)]
+    steps -= 1
+    path = [(row, col)]
+    directions = []
+
+    while steps >= 0:
+        if (row - 1, col) in visited and visited[(row - 1, col)] == steps:
+            path.append((row - 1, col))
+            directions.append("D")
+            row -= 1
+        if (row + 1, col) in visited and visited[(row + 1, col)] == steps:
+            path.append((row + 1, col))
+            directions.append("U")
+            row += 1
+        if (row, col - 1) in visited and visited[(row, col - 1)] == steps:
+            path.append((row, col - 1))
+            directions.append("R")
+            col -= 1
+        if (row, col + 1) in visited and visited[(row, col + 1)] == steps:
+            path.append((row, col + 1))
+            directions.append("L")
+            col += 1
+        steps -= 1
+
+    path.reverse()
+    directions.reverse()
+    return (path, directions)
+
+
+# ------------------------------ Basic Testing --------------------------------#
+
+if __name__ == "__main__":
+
+    puzzle = [
+        ["-", "-", "-", "-", "-"],
+        ["-", "-", "#", "-", "-"],
+        ["-", "-", "-", "-", "-"],
+        ["#", "-", "#", "#", "-"],
+        ["-", "#", "-", "-", "-"],
+    ]
+
+    source = (0, 2)
+    destination = (2, 2)
+    # source = (0, 0)
+    # destination = (4, 4)
+    result = solve_puzzle(puzzle, source, destination)
+    print(result)