Workshop › Battleship › Step 6 of 35

A random fleet

What we are doing

A fleet has ships of length 5, 4, 3, 3 and 2. Each ship tries random spots until it fits on the sea without overlapping a ship already placed.

```js
const SHIPS = [5, 4, 3, 3, 2]

// A random fleet: each ship tries random spots until it fits on the sea without overlapping another.
function placeFleet() {
  const taken = grid(false)
  return SHIPS.map((length) => {
    for (;;) {
      const down = Math.random() < 0.5
      const r = Math.floor(Math.random() * (down ? N - length + 1 : N))
      const c = Math.floor(Math.random() * (down ? N : N - length + 1))
      const cells = shipCells(r, c, length, down)
      if (cells.some(([cr, cc]) => taken[cr][cc])) continue
      for (const [cr, cc] of cells) taken[cr][cc] = true
      return { cells }
    }
  })
}
```

What it means

SHIPS.map(...) turns each length into a ship; the result is the list of five ships.
for (;;) loops forever; continue tries again, return leaves with a ship that fits.
The start is chosen so the whole ship fits: a ship of 5 going down can start only in rows 0 to 5.
some asks whether any of its squares is already taken; if not, they are marked taken.

Your turn

Under const N = 10 write SHIPS.
Above function drawSea(, write placeFleet with its comment, followed by an empty line.

Skills: Loops, Arrays and objects

← Grids and ships as lists Two fleets →

All steps