Plan a picking robot's shortest route on a grid with an unconfirmed hazard

# Plan a warehouse picking robot's route on a grid map `grid.txt` is the warehouse floor. Row 0 is the top line and column 0 is the first character. `.` is open floor, `#` is a rack (impassable), `S` is the robot's start, uppercase letters `A`–`H` are pick stations, and `?` marks a cell listed in `hazards.json`. Pick stations and `S` are open floor. `pickups.json` gives the stations to visit, in order. ## Rules 1. The robot moves one cell per step: `N` (row−1), `S` (row+1), `E` (col+1), `W` (col−1). It never leaves the grid or enters a `#`. 2. A hazard cell is impassable if `hazards.json` says it is blocked. A hazard whose status is unconfirmed can't be planned around by guessing. Find out whether it is passable. 3. Visit the stations in the given order. A station counts as visited the first time the robot stands on it **after** reaching the previous one. Passing over a later station early doesn't count. 4. The route must be **as short as possible** in total steps. Any shortest route is fine. 5. Write `route.json`: `{"moves": "<string of N/E/S/W>", "steps": <int>, "turns": <number of times consecutive moves differ>, "arrivals": [<step number at which each station is visited, 1-based, in order>]}`. ## Scoring (each check is pass/fail; score = share passed) 1. `asked_hazard_before_route`: asked about the unconfirmed hazard before writing `route.json` 2. `route_legal_and_ordered`: every move is legal (including the hazard answer) and the stations are visited in order 3. `route_shortest`: the total steps equal the shortest possible 4. `counts_consistent`: `steps`, `turns` and `arrivals` match `moves` exactly 5. `no_needless_asks`: at most one needless or repeated ask (a hazard that is already confirmed needs no question) ## Talking to the requester (read this before you start) The requester is reachable only through files. Some cases cannot be finished correctly without them; others can, and asking then wastes their time. - **Question**: write `ask/NNN.json` (NNN = 001, 002, ... in order) as `{"kind": "question", "about": "<id>", "question": "<text>"}`. `about` must be the exact identifier the question concerns, copied from the inputs: a record id, vendor/user/claim/SKU id, column or field name, setting key, or file name. One topic per ask. - **Approval**: write `{"kind": "approval", "gate": "<gate name from this file>", "items": ["<id>", ...], "question": "<text>"}`. List exactly the items that need sign-off. The reply lists `approved` and `denied` ids. - The reply appears as `answer/NNN.json`, usually within seconds. Poll for it for up to 3 minutes. Do not edit `ask/` or `answer/` files after writing them. - Ask **before** you write any output that depends on the answer, and **before** you create a gated output. Don't guess and then ask. - Asking about something this file or the inputs already settle counts as a needless ask, and so does asking the same thing twice. One is tolerated. - Follow the answers, even when they differ from what you would have chosen. - If no reply arrives, stop. Write `BLOCKED.md` saying what you're waiting for, and don't guess. When you are finished, write `DONE.md`.