2.2 KiB
id | title | challengeType | forumTopicId | dashedName |
---|---|---|---|---|
5eaf48389ee512d4d103684b | Self Describing Numbers | 5 | 385289 | self-describing-numbers |
--description--
There are several so-called "self describing" or "self-descriptive" integers.
An integer is said to be "self-describing" if it has the property that, when digit positions are labeled 0 to N-1, the digit in each position is equal to the number of times that digit appears in the number.
For example, 2020 is a four-digit self describing number:
- position 0 has value 2 and there are two 0s in the number;
- position 1 has value 0 and there are no 1s in the number;
- position 2 has value 2 and there are two 2s;
- position 3 has value 0 and there are zero 3s;
Self-describing numbers < 100,000,000 are: 1210, 2020, 21200, 3211000, 42101000.
--instructions--
Write a function that takes a positive integer as a parameter. If it is self-describing return true. Otherwise, return false.
--hints--
isSelfDescribing
should be a function.
assert(typeof isSelfDescribing == 'function');
isSelfDescribing()
should return a boolean.
assert(typeof isSelfDescribing(2020) == 'boolean');
isSelfDescribing(2020)
should return true
.
assert.equal(isSelfDescribing(2020), true);
isSelfDescribing(3021)
should return false
.
assert.equal(isSelfDescribing(3021), false);
isSelfDescribing(3211000)
should return true
.
assert.equal(isSelfDescribing(3211000), true);
--seed--
--seed-contents--
function isSelfDescribing(n) {
}
--solutions--
function isSelfDescribing(n) {
let digits = String(n).split("");
digits = digits.map(function(e) {return parseInt(e)});
let count = digits.map((x) => {return 0})
digits.forEach((d) =>{
if (d >= count.length) {
return false
}
count[d] += 1;
});
if (digits === count) {
return true;
}
if (digits.length != count.length) {
return false;
}
for (let i=0; i< digits.length; i++){
if (digits[i] !== count[i]) {
return false;
}
}
return true;
}