Add new brain-prime game

Author: thedoorbell

bin/brain-prime.js

@@ -0,0 +1,5 @@
+#!/usr/bin/env node
+
+import run from '../src/games/prime.js';
+
+run();

src/games/prime.js

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+import playGame from '../index.js';
+
+const rules = 'Answer "yes" if given number is prime. Otherwise answer "no".';
+
+const askIfPrime = () => {
+  const num = Math.floor(Math.random() * 100) + 1;
+  let divisors = 1;
+  let correctAnswer = '';
+
+  for (let i = 2; i <= num; i += 1) {
+    if (num % i === 0) {
+      divisors += 1;
+      if (divisors === 3) {
+        break;
+      }
+    }
+  }
+  correctAnswer = divisors === 2 ? 'yes' : 'no';
+
+  return [num, correctAnswer];
+};
+
+export default () => playGame(rules, askIfPrime);