Find the fleet / every shot has one identity

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<section class="panel gameArea"><div class="scorebar"><div>Unique shots<strong id="shots">0</strong></div><div>Hits<strong id="hits">0</strong></div><div>Ships sunk<strong id="sunk">0 / 2</strong></div><div>Ships remaining<strong id="shipsRemaining">2</strong></div><div>Unhit cells<strong id="remaining">5</strong></div></div><div id="board" class="fleetBoard" role="group" aria-label="Attack coordinates, rows 0 to 5 and columns 0 to 5"></div><p id="message" class="state" role="status">Choose an unknown coordinate. Two ships occupy five cells.</p><p class="caption">Unknown · / hit × / miss ○ / sunk ■. Row and column labels use 0–5.</p><form id="form" novalidate><div class="row"><div><label for="row">Row</label><input id="row" inputmode="numeric" placeholder="0–5"></div><div><label for="col">Column</label><input id="col" inputmode="numeric" placeholder="0–5"></div></div><div class="buttons"><button class="primary" id="attack">Attack coordinate</button><button type="button" id="reset">Reset fleet and shots</button></div></form></section>
<section class="panel below"><h2>Shot ledger</h2><div id="ledger" class="record">No shots fired.</div><p class="muted">This is a fixed original one-sided fleet exercise, not multiplayer or a computer opponent. Repeated shots never add to the counters; all shots stop after the fleet is sunk. Reset restores the same fleet. The source contains its coordinates; this is not a secrecy or security boundary.</p><a href="https://www2.cs.arizona.edu/classes/cs120/fall17/ASSIGNMENTS/assg06/battleship.html">Unique attacks, hits and per-ship completion reference</a></section><details class="panel below"><summary>Manual browser checks / pending parent review</summary><table><thead><tr><th>Action</th><th>Expected observation</th></tr></thead><tbody><tr><td>Attack 1,1 twice, then 0,0</td><td>Two unique shots, one hit, no ships sunk.</td></tr><tr><td>Then attack 1,2; 1,3; 3,4; 4,4</td><td>Six unique shots, five hits, two sunk, zero ships remaining.</td></tr><tr><td>Activate a repeated hit or sunk cell by keyboard</td><td>Focus remains usable; no additional shot or sinking.</td></tr><tr><td>Attack after fleet complete, then Reset</td><td>No terminal update; Reset restores all 36 unknown cells.</td></tr></tbody></table><p class="muted">Also inspect focus, touch controls and overflow at 360, 720 and 1440 px. Local scripted logic checks are retained separately; these browser observations remain pending.</p></details><footer class="below muted">Local working example. Edits last only while this page is open.</footer></main><script data-app>
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const original=[{id:'S1',length:3,cells:[[1,1],[1,2],[1,3]]},{id:'S2',length:2,cells:[[3,4],[4,4]]}];const key=(r,c)=>r+','+c;
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class Fleet{constructor(fleet=original){validateFleet(fleet);this.fleet=structuredClone(fleet);this.epoch=0;this.reset()}reset(){this.epoch++;this.shots=new Set;this.announcements=[]}summary(){const hits=this.fleet.reduce((n,s)=>n+s.cells.filter(c=>this.shots.has(key(...c))).length,0),sunk=this.fleet.filter(s=>s.cells.every(c=>this.shots.has(key(...c))));return {shots:this.shots.size,hits,sunk:sunk.length,shipsRemaining:this.fleet.length-sunk.length,remaining:this.fleet.reduce((n,s)=>n+s.length,0)-hits,won:sunk.length===this.fleet.length}}attack(r,c,epoch=this.epoch){if(epoch!==this.epoch)return {kind:'stale'};if(!Number.isInteger(r)||!Number.isInteger(c)||r<0||r>5||c<0||c>5)throw Error('Enter a row and column from 0 to 5.');if(this.summary().won)return {kind:'finished'};const k=key(r,c);if(this.shots.has(k))return {kind:'repeat'};this.shots.add(k);const ship=this.fleet.find(s=>s.cells.some(cell=>key(...cell)===k));if(!ship)return {kind:'miss'};if(ship.cells.every(cell=>this.shots.has(key(...cell)))){this.announcements.push(ship.id);return {kind:'sunk',ship:ship.id,won:this.summary().won}}return {kind:'hit'}}cell(r,c){if(!this.shots.has(key(r,c)))return 'unknown';const s=this.fleet.find(s=>s.cells.some(p=>key(...p)===key(r,c)));return !s?'miss':s.cells.every(p=>this.shots.has(key(...p)))?'sunk':'hit'}}
function coordinate(s){s=String(s).trim();if(!/^[0-5]$/.test(s))throw Error('Enter a single whole coordinate from 0 to 5. Blank is missing.');return +s}
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