draft tutorial revisions

docs/cookbook/grid/grid_dijkstra_multi.py

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+"""McRogueFace - Dijkstra Distance Maps (multi)
+
+Documentation: https://mcrogueface.github.io/cookbook/grid_dijkstra
+Repository: https://github.com/jmccardle/McRogueFace/blob/master/docs/cookbook/grid/grid_dijkstra_multi.py
+
+This code is extracted from the McRogueFace documentation and can be
+run directly with: ./mcrogueface path/to/this/file.py
+"""
+
+# Cache Dijkstra maps when possible
+class CachedDijkstra:
+    """Cache Dijkstra computations."""
+
+    def __init__(self, grid):
+        self.grid = grid
+        self.cache = {}
+        self.cache_valid = False
+
+    def invalidate(self):
+        """Call when map changes."""
+        self.cache = {}
+        self.cache_valid = False
+
+    def get_distance(self, from_x, from_y, to_x, to_y):
+        """Get cached distance or compute."""
+        key = (to_x, to_y)  # Cache by destination
+
+        if key not in self.cache:
+            self.grid.compute_dijkstra(to_x, to_y)
+            # Store all distances from this computation
+            self.cache[key] = self._snapshot_distances()
+
+        return self.cache[key].get((from_x, from_y), float('inf'))
+
+    def _snapshot_distances(self):
+        """Capture current distance values."""
+        grid_w, grid_h = self.grid.grid_size
+        distances = {}
+        for x in range(grid_w):
+            for y in range(grid_h):
+                dist = self.grid.get_dijkstra_distance(x, y)
+                if dist != float('inf'):
+                    distances[(x, y)] = dist
+        return distances