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)`