Find robots matching obstacle-distance signature

You are given a 2D grid and a distance signature dist = [left, top, bottom, right].

Grid

Each cell is one of:

• O : a robot
• E : empty
• X : obstacle

The boundary outside the grid is also considered an obstacle (i.e., moving off the grid in any direction hits an obstacle immediately).

Distance signature

For any cell (r, c), define:

• left = the number of non-obstacle cells strictly between (r,c) and the nearest obstacle when moving left in the same row.
• top = the number of non-obstacle cells strictly between (r,c) and the nearest obstacle when moving up in the same column.
• bottom = the number of non-obstacle cells strictly between (r,c) and the nearest obstacle when moving down in the same column.
• right = the number of non-obstacle cells strictly between (r,c) and the nearest obstacle when moving right in the same row.

Notes:

• If the adjacent cell in that direction is an obstacle (or you would immediately leave the grid), the distance in that direction is 0 .
• Obstacles ( X ) block the line of sight; only the nearest obstacle in that direction matters.

Task

Return the coordinates of all robots (O cells) whose distance signature equals the given dist.

Input / Output (you may assume)

• Input: grid as an R x C matrix of characters, and integer array dist of length 4.
• Output: a list of coordinates [(r1,c1), (r2,c2), ...] for all matching robots (any order).

Constraints (reasonable interview assumptions)

• 1 <= R, C <= 2000
• grid[r][c] ∈ { 'O', 'E', 'X' }
• 0 <= dist[i] <= max(R,C)