Add BFS algorithm

survival/pathfinding.py

@@ -0,0 +1,54 @@
+from collections import deque as Queue
+
+
+def valid_neighbor(n, game_map, visited):
+    if n[0] < 0 or n[1] < 0 or n[0] >= game_map.width or n[1] >= game_map.height:
+        return False
+    if visited[n[0]][n[1]]:
+        return False
+    if game_map.is_colliding(n):
+        return False
+
+    return True
+
+
+def breadth_first_search(game_map, start, target):
+    visited = [[False for _ in range(game_map.width)] for _ in range(game_map.height)]
+    q = Queue()
+    came_from = dict()
+    came_from[start] = (-1, -1)
+
+    q.append(start)
+    visited[start[0]][start[1]] = True
+
+    while len(q) > 0:
+        cell = q.popleft()
+
+        if cell == target:
+            break
+
+        neighbors = [
+            (cell[0] - 1, cell[1]),
+            (cell[0], cell[1] + 1),
+            (cell[0] + 1, cell[1]),
+            (cell[0], cell[1] - 1),
+        ]
+
+        for neighbor in neighbors:
+            if valid_neighbor(neighbor, game_map, visited):
+                q.append(neighbor)
+                visited[neighbor[0]][neighbor[1]] = True
+                came_from[neighbor] = cell
+
+    path = list()
+    current = target
+    if came_from.get(start, None) is not None:
+        path.append(start)
+        return path
+
+    while current != start:
+        path.append(current)
+        current = came_from[current]
+
+    path.append(start)
+    return path