You are given a one-dimensional board represented as an array of tiles start. Each tile is one of three values: "R" (red), "B" (black), or "_" (empty). Red tiles can only move to the right; black tiles can only move to the left. In a single move, a tile can either:

1. Slide into an adjacent empty space in its allowed direction, or
2. Jump over exactly one tile of the opposite color into an empty space in its allowed direction.