2.2 KiB
2.2 KiB
id | challengeType | title |
---|---|---|
5900f39e1000cf542c50feb1 | 5 | Problem 50: Consecutive prime sum |
Description
Instructions
Tests
tests:
- text: <code>consecutivePrimeSum(1000)</code> should return 953.
testString: assert.strictEqual(consecutivePrimeSum(1000), 953, '<code>consecutivePrimeSum(1000)</code> should return 953.');
- text: <code>consecutivePrimeSum(1000000)</code> should return 997651.
testString: assert.strictEqual(consecutivePrimeSum(1000000), 997651, '<code>consecutivePrimeSum(1000000)</code> should return 997651.');
Challenge Seed
function consecutivePrimeSum(limit) {
// Good luck!
return true;
}
consecutivePrimeSum(1000000);
Solution
function consecutivePrimeSum(limit) {
function isPrime(num) {
if (num < 2) {
return false;
} else if (num === 2) {
return true;
}
const sqrtOfNum = Math.floor(num ** 0.5);
for (let i = 2; i <= sqrtOfNum + 1; i++) {
if (num % i === 0) {
return false;
}
}
return true;
}
function getPrimes(limit) {
const primes = [];
for (let i = 0; i <= limit; i++) {
if (isPrime(i)) primes.push(i);
}
return primes;
}
const primes = getPrimes(limit);
let primeSum = [...primes];
primeSum.reduce((acc, n, i) => {
primeSum[i] += acc;
return acc += n;
}, 0);
for (let j = primeSum.length - 1; j >= 0; j--) {
for (let i = 0; i < j; i++) {
const sum = primeSum[j] - primeSum[i];
if (sum > limit) break;
if (isPrime(sum) && primes.indexOf(sum) > -1) return sum;
}
}
}