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Refactor maze generation and solvability check #1

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2f9940b
Refactor maze generation and solvability check
JanKrivanek Mar 30, 2026
49b20ab
Fix compilation error: compare Position instead of CellType with maze…
JanKrivanek Mar 30, 2026
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19 changes: 13 additions & 6 deletions src/MazeSolver/Services/MazeGenerator.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -23,10 +23,6 @@ public Maze Generate(int width, int height)

var maze = new Maze(width, height);

// Carve paths using DFS from (1, 1)
var startPos = new Position(1, 1);
CarvePath(maze, startPos);

// Set entry at top-left accessible position
maze.SetEntry(new Position(1, 0));
maze[1, 0].Type = CellType.Entry;
Expand All @@ -39,8 +35,12 @@ public Maze Generate(int width, int height)
maze[1, 1].Type = CellType.Path;
maze[width - 2, height - 2].Type = CellType.Path;

// Carve paths using DFS from (1, 1)
var startPos = new Position(1, 1);
bool isSolvable = CarvePath(maze, startPos);

// Verify the maze is solvable
if (!IsSolvable(maze))
if (!isSolvable)
{
Log.Warning("Generated maze was not solvable, regenerating...");
return Generate(width, height);
Comment on lines 35 to 46
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@qodo-code-review qodo-code-review Bot Mar 30, 2026

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4. Exit unreachable by dfs 🐞 Bug ✓ Correctness

With enforced odd dimensions, the exit is placed at y = height - 1 (even), but CarvePath moves
in steps of 2 from y = 1 (odd), so it can never reach the exit position; additionally, pre-marking
(width-2,height-2) as Path prevents carving into the only cell adjacent to the exit.
Agent Prompt 
### Issue description
The current `CarvePath`-based solvability detection cannot succeed with the current exit placement/move step and the pre-opened `(width-2,height-2)` cell.

### Issue Context
- `Generate()` normalizes dimensions to odd.
- Exit is placed at `(width-2, height-1)`.
- `CarvePath` moves by +/-2, so it only visits odd coordinates starting from `(1,1)`.
- `(width-2,height-2)` is set to `Path` before carving, but the carve only enters `Wall` cells.

### Fix Focus Areas
- src/MazeSolver/Services/MazeGenerator.cs[20-47]
- src/MazeSolver/Services/MazeGenerator.cs[53-85]
- src/MazeSolver/Services/MazeGenerator.cs[96-128]

### Implementation direction (choose one)
1) Restore BFS verification: keep `CarvePath` as `void` and use `IsSolvable(maze)` after carving; or
2) If keeping `CarvePath` returning `bool`, make the goal a reachable carve-cell (e.g., reaching `(width-2,height-2)`), ensure that cell is not pre-marked as `Path` before carving (or allow carving/connect-to it), and propagate return values up the recursion chain.

ⓘ Copy this prompt and use it to remediate the issue with your preferred AI generation tools

Expand All @@ -50,7 +50,7 @@ public Maze Generate(int width, int height)
return maze;
}

private void CarvePath(Maze maze, Position pos)
private bool CarvePath(Maze maze, Position pos)
{
maze[pos].Type = CellType.Path;

Expand All @@ -64,6 +64,11 @@ private void CarvePath(Maze maze, Position pos)
var newY = pos.Y + dy;
var newPos = new Position(newX, newY);

if (newPos == maze.Exit)
{
return true;
}

// Check if the new position is valid and unvisited
if (maze.IsInBounds(newPos) && maze[newPos].Type == CellType.Wall)
{
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Expand All @@ -75,6 +80,8 @@ private void CarvePath(Maze maze, Position pos)
CarvePath(maze, newPos);
}
}

return false;
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@qodo-code-review qodo-code-review Bot Mar 30, 2026

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3. Carvepath result not propagated 🐞 Bug ✓ Correctness

Recursive calls to CarvePath ignore the returned boolean, so even if a deeper recursion determines
reachability, the initial call can still return false, causing repeated regeneration in
Generate().
Agent Prompt 
### Issue description
`CarvePath` now returns `bool` but recursive invocations discard the return, so the top-level solvability signal is lost.

### Issue Context
`Generate()` depends on `bool isSolvable = CarvePath(...)`. For DFS-style discovery, successful results must be propagated upward (e.g., `if (CarvePath(...)) return true;`).

### Fix Focus Areas
- src/MazeSolver/Services/MazeGenerator.cs[38-47]
- src/MazeSolver/Services/MazeGenerator.cs[73-85]

ⓘ Copy this prompt and use it to remediate the issue with your preferred AI generation tools

}

private void Shuffle<T>(List<T> list)
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