Knight Minimum Moves with a Fixed Bishop

You are given an n-by-n chessboard whose rows and columns are numbered from 0 to n - 1. A knight starts at (startRow, startCol) and must reach (endRow, endCol).
A bishop remains fixed at (bishopRow, bishopCol). The knight may not occupy the bishop's square or any square the bishop attacks. Because the board contains no other pieces, the bishop attacks every in-bounds square on either diagonal through its position.
On each move, the knight changes its row by 2 and its column by 1, or its row by 1 and its column by 2, with either sign. Return the minimum number of legal knight moves needed to reach the target. Return -1 if the start or target is unsafe, or if the target cannot be reached.

Function
minKnightMoves(n: int, startRow: int, startCol: int, endRow: int, endCol: int, bishopRow: int, bishopCol: int) → int

Examples
Example 1
n = 9
startRow = 4
startCol = 4
endRow = 4
endCol = 8
bishopRow = 0
bishopCol = 1
return = 2
The target is reachable in two legal knight moves, and neither visited square lies on a bishop diagonal.
Example 2
n = 5
startRow = 0
startCol = 0
endRow = 4
endCol = 3
bishopRow = 2
bishopCol = 2
return = -1
The starting square lies on the bishop's diagonal, so no legal route exists.

Constraints
4 <= n <= 150
0 <= startRow, startCol, endRow, endCol, bishopRow, bishopCol < n
The bishop remains fixed for the entire route.
The knight may not occupy the bishop's square or any square on either bishop diagonal.

Run BFS from the start square with a queue and a visited grid. Each pop expands eight knight moves. Skip any move that's out of bounds, visited, or unsafe. A square is unsafe if it's the bishop's square or if abs(r - bishopRow) equals abs(c - bishopCol), which covers both diagonals without precomputing anything. BFS gives the minimum move count because every move costs one. The common pitfalls: forgetting to check the start and target before searching, which is exactly what Example 2 tests. Also mark squares visited when you enqueue, not when you dequeue, or the queue balloons. And if start equals target and it's safe, return 0. That's the edge case people skip. The grid has at most 22,500 cells, so time isn't a worry. If your mind goes blank mid-assessment, StealthCoder is the hedge that surfaces the BFS skeleton while you focus on the unsafe-square check.

Drill it cold or hedge it with StealthCoder. Either way, don't walk into the OA hoping you remember the trick.