1.6 KiB
1.6 KiB
id | challengeType | title | forumTopicId |
---|---|---|---|
5900f3761000cf542c50fe89 | 5 | Problem 10: Summation of primes | 301723 |
Description
The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.
Find the sum of all the primes below n
.
Instructions
Tests
tests:
- text: <code>primeSummation(17)</code> should return a number.
testString: assert(typeof primeSummation(17) === 'number');
- text: <code>primeSummation(17)</code> should return 41.
testString: assert.strictEqual(primeSummation(17), 41);
- text: <code>primeSummation(2001)</code> should return 277050.
testString: assert.strictEqual(primeSummation(2001), 277050);
- text: <code>primeSummation(140759)</code> should return 873608362.
testString: assert.strictEqual(primeSummation(140759), 873608362);
- text: <code>primeSummation(2000000)</code> should return 142913828922.
testString: assert.strictEqual(primeSummation(2000000), 142913828922);
Challenge Seed
function primeSummation(n) {
return true;
}
primeSummation(2000000);
Solution
function primeSummation(n) {
if (n < 3) { return 0 };
let nums = [0, 0, 2];
for (let i = 3; i < n; i += 2){
nums.push(i);
nums.push(0);
}
let sum = 2;
for (let i = 3; i < n; i += 2){
if (nums[i] !== 0){
sum += nums[i];
for (let j = i*i; j < n; j += i){
nums[j] = 0;
}
}
}
return sum;
}