fix(curriculum): rework Project Euler 87 (#42194)

* fix: rework challenge to use argument in function

* fix: add solution

* fix: position equations evenly between paragraphs
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gikf
2021-05-27 09:44:40 +02:00
committed by GitHub
parent 00b76c0389
commit 2f901f9ffe

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@ -8,29 +8,53 @@ dashedName: problem-87-prime-power-triples
# --description--
The smallest number expressible as the sum of a prime square, prime cube, and prime fourth power is 28. In fact, there are exactly four numbers below fifty that can be expressed in such a way:
The smallest number expressible as the sum of a prime square, prime cube, and prime fourth power is `28`. In fact, there are exactly four numbers below fifty that can be expressed in such a way:
<div style='margin-left: 4em;'>
28 = 2<sup>2</sup> + 2<sup>3</sup> + 2<sup>4</sup><br>
33 = 3<sup>2</sup> + 2<sup>3</sup> + 2<sup>4</sup><br>
49 = 5<sup>2</sup> + 2<sup>3</sup> + 2<sup>4</sup><br>
47 = 2<sup>2</sup> + 3<sup>3</sup> + 2<sup>4</sup>
</div>
</div><br>
How many numbers below fifty million can be expressed as the sum of a prime square, prime cube, and prime fourth power?
How many numbers below `n` can be expressed as the sum of a prime square, prime cube, and prime fourth power?
# --hints--
`primePowerTriples()` should return a number.
`primePowerTriples(50)` should return a number.
```js
assert(typeof primePowerTriples() === 'number');
assert(typeof primePowerTriples(50) === 'number');
```
`primePowerTriples()` should return 1097343.
`primePowerTriples(50)` should return `4`.
```js
assert.strictEqual(primePowerTriples(), 1097343);
assert.strictEqual(primePowerTriples(50), 4);
```
`primePowerTriples(10035)` should return `684`.
```js
assert.strictEqual(primePowerTriples(10035), 684);
```
`primePowerTriples(500000)` should return `18899`.
```js
assert.strictEqual(primePowerTriples(500000), 18899);
```
`primePowerTriples(5000000)` should return `138932`.
```js
assert.strictEqual(primePowerTriples(5000000), 138932);
```
`primePowerTriples(50000000)` should return `1097343`.
```js
assert.strictEqual(primePowerTriples(50000000), 1097343);
```
# --seed--
@ -38,16 +62,70 @@ assert.strictEqual(primePowerTriples(), 1097343);
## --seed-contents--
```js
function primePowerTriples() {
function primePowerTriples(n) {
return true;
}
primePowerTriples();
primePowerTriples(50);
```
# --solutions--
```js
// solution required
function primePowerTriples(n) {
function getSievePrimes(max) {
const primes = [];
const primesMap = new Array(max).fill(true);
primesMap[0] = false;
primesMap[1] = false;
for (let i = 2; i <= max; i += 2) {
if (primesMap[i]) {
primes.push(i);
for (let j = i * i; j <= max; j = j + i) {
primesMap[j] = false;
}
}
if (i === 2) {
i = 1;
}
}
return primes;
}
function getPowersSummed(numbers, powers, limit, curSum) {
if (curSum >= limit) {
return [];
} else if (powers.length === 0) {
return [curSum];
}
const powersSummed = [];
const curPower = powers[0];
const powersLeft = powers.slice(1);
for (let i = 0; i < numbers.length; i++) {
const curNumber = numbers[i];
const nextSum = curSum + curNumber ** curPower;
if (nextSum >= limit) {
return powersSummed;
}
const result = getPowersSummed(
numbers,
powersLeft,
limit,
curSum + curNumber ** curPower
);
powersSummed.push(...result);
}
return powersSummed;
}
const maximumBaseNumber = Math.floor(Math.sqrt(n - 2 ** 3 - 2 ** 4)) + 1;
const primes = getSievePrimes(maximumBaseNumber);
const uniqueSums = new Set(getPowersSummed(primes, [2, 3, 4], n, 0));
return uniqueSums.size;
}
```