Add BFS solving algorithm

package.json

@@ -10,6 +10,7 @@
     "test": "vitest"
   },
   "dependencies": {
+    "@datastructures-js/deque": "^1.0.4",
     "async-mutex": "^0.5.0",
     "immer": "^10.1.1",
     "next": "14.2.4",

src/lib/algorithms/solving/BFS.ts

@@ -0,0 +1,41 @@
+import { MazeCell } from "@/lib/MazeCell";
+import { MazeSolver } from "./MazeSolver";
+import { Deque } from "@datastructures-js/deque";
+import { buildPath } from "./pathUtils";
+
+export class BFS extends MazeSolver {
+  private queue = new Deque<MazeCell>();
+  private cameFrom = new Map<MazeCell, MazeCell>();
+
+  protected _step(): [boolean, Readonly<MazeCell>[]] {
+    const changes: MazeCell[] = [];
+
+    // Go through one queue level
+    const queueSize = this.queue.size();
+    for (let i = 0; i < queueSize; ++i) {
+      const current = this.queue.popFront();
+
+      if (current === this.end) {
+        this._path = buildPath(this.cameFrom, this.end);
+        return [true, []];
+      }
+
+      for (const neighbor of current.connections) {
+        if (neighbor.state === "solid") {
+          neighbor.state = "partial";
+          this.queue.pushBack(neighbor);
+          this.cameFrom.set(neighbor, current);
+          changes.push(neighbor);
+        }
+      }
+    }
+
+    return [this.queue.isEmpty(), changes];
+  }
+
+  protected initialize(): Readonly<MazeCell>[] {
+    this.start.state = "partial";
+    this.queue.pushBack(this.start);
+    return [this.start];
+  }
+}

src/lib/algorithms/solving/pathUtils.ts

@@ -0,0 +1,14 @@
+import { MazeCell } from "@/lib/MazeCell";
+
+export function buildPath(
+  cameFrom: Map<MazeCell, MazeCell>,
+  end: MazeCell,
+): MazeCell[] {
+  const path: MazeCell[] = [];
+  let current: MazeCell | null = end;
+  while (current !== null) {
+    path.unshift(current);
+    current = cameFrom.get(current) ?? null;
+  }
+  return path.toReversed();
+}