1.9 KiB
1.9 KiB
id | title | challengeType | forumTopicId | dashedName |
---|---|---|---|---|
595668ca4cfe1af2fb9818d4 | Harshad or Niven series | 5 | 302281 | harshad-or-niven-series |
--description--
The Harshad or Niven numbers are positive integers ≥ 1 that are divisible by the sum of their digits.
For example, 42
is a Harshad number as 42
is divisible by (4 + 2)
without remainder.
Assume that the series is defined as the numbers in increasing order.
--instructions--
Implement a function to generate successive members of the Harshad sequence.
Use it to list the first twenty members of the sequence and list the first Harshad number greater than 1000.
--hints--
isHarshadOrNiven
should be a function.
assert(typeof isHarshadOrNiven === 'function');
isHarshadOrNiven()
should return {"firstTwenty": [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 18, 20, 21, 24, 27, 30, 36, 40, 42],"firstOver1000": 1002}
assert.deepEqual(isHarshadOrNiven(), res);
--seed--
--after-user-code--
const res = {
firstTwenty: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 18, 20, 21, 24, 27, 30, 36, 40, 42],
firstOver1000: 1002
};
--seed-contents--
function isHarshadOrNiven() {
const res = {
firstTwenty: [],
firstOver1000: undefined
};
// Only change code below this line
return res;
}
--solutions--
function isHarshadOrNiven() {
const res = {
firstTwenty: [],
firstOver1000: undefined
};
function isHarshad(n) {
let s = 0;
const nStr = n.toString();
for (let i = 0; i < nStr.length; ++i) {
s += parseInt(nStr.charAt(i), 10);
}
return n % s === 0;
}
let count = 0;
const harshads = [];
for (let n = 1; count < 20; ++n) {
if (isHarshad(n)) {
count++;
harshads.push(n);
}
}
res.firstTwenty = harshads;
let h = 1000;
while (!isHarshad(++h));
res.firstOver1000 = h;
return res;
}