Meta VO 面试真题解析：Maze Solver 完成缺失功能与 BFS 解题思路

Background

This is a small codebase related to mazes. It has some basic utilities to parse a maze from a string representation, print out a maze, and attempt basic maze solving. However, an intern from summers past wrote the code, so there might be some bugs. They also didn’t quite finish their summer project, so let’s:

• uncomment the tests
• fix any bugs
• finish any functionality they hadn’t done yet

Completing the Question

Check out the unit tests. There are four files:

• p1_test_maze_printer
• p2_test_maze_solver
• p3_test_maze_solve_hard
• p4_test_maze_solver_with_key

You can go in order, p1 to p4, to complete the question. Make sure to uncomment the tests to complete each part.

TODO: Uncomment the following code as you implement the proper logic for MazePrinter.

Uncomment to test solving the big maze

@Test
public void testCanSolveWithChutes() {
    /* Test that we can solve a maze with chutes. */
    MazeSolver solver = new MazeSolver(mazeWithChutes);
    assertTrue(solver.hasSolutionViaBFS());
}

@Test
public void testCanSolveWithImpossible() {
    /* Test that can't solve a maze with impossible chutes. */
    MazeSolver solver = new MazeSolver(mazeWithImpossibleChutes);
    assertFalse(solver.hasSolutionViaBFS());
}

这道 Meta VO 题本质上是一个迷宫求解与代码补全任务：你需要先补齐被注释掉的单元测试，再修复 MazePrinter 和 MazeSolver 中的缺失或错误逻辑。核心思路通常是把迷宫抽象成图，用 BFS 判断从起点到终点是否可达；如果题目里包含 chute、key 等特殊格子，则在搜索时把它们当作状态转移规则的一部分，必要时将“当前位置 + 是否持有钥匙”等信息一起作为访问状态，避免重复搜索和错误判定。