67 lines
1.5 KiB
Markdown
67 lines
1.5 KiB
Markdown
|
---
|
|||
|
|
id: 5900f3841000cf542c50fe97
|
|||
|
|
title: 'Problem 24: Lexicographic permutations'
|
|||
|
|
challengeType: 5
|
|||
|
|
forumTopicId: 301885
|
|||
|
|
dashedName: problem-24-lexicographic-permutations
|
|||
|
|
---
|
|||
|
|
|
|||
|
|
# --description--
|
|||
|
|
|
|||
|
|
A permutation is an ordered arrangement of objects. For example, 3124 is one possible permutation of the digits 1, 2, 3 and 4. If all of the permutations are listed numerically or alphabetically, we call it lexicographic order. The lexicographic permutations of 0, 1 and 2 are:
|
|||
|
|
|
|||
|
|
<div style='text-align: center;'>012 021 102 120 201 210</div>
|
|||
|
|
|
|||
|
|
What is the `n`th lexicographic permutation of the digits 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9?
|
|||
|
|
|
|||
|
|
# --hints--
|
|||
|
|
|
|||
|
|
`lexicographicPermutations(699999)` should return a number.
|
|||
|
|
|
|||
|
|
```js
|
|||
|
|
assert(typeof lexicographicPermutations(699999) === 'number');
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
`lexicographicPermutations(699999)` should return 1938246570.
|
|||
|
|
|
|||
|
|
```js
|
|||
|
|
assert(lexicographicPermutations(699999) == 1938246570);
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
`lexicographicPermutations(899999)` should return 2536987410.
|
|||
|
|
|
|||
|
|
```js
|
|||
|
|
assert(lexicographicPermutations(899999) == 2536987410);
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
`lexicographicPermutations(900000)` should return 2537014689.
|
|||
|
|
|
|||
|
|
```js
|
|||
|
|
assert(lexicographicPermutations(900000) == 2537014689);
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
`lexicographicPermutations(999999)` should return 2783915460.
|
|||
|
|
|
|||
|
|
```js
|
|||
|
|
assert(lexicographicPermutations(999999) == 2783915460);
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
# --seed--
|
|||
|
|
|
|||
|
|
## --seed-contents--
|
|||
|
|
|
|||
|
|
```js
|
|||
|
|
function lexicographicPermutations(n) {
|
|||
|
|
|
|||
|
|
return n;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
lexicographicPermutations(999999);
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
# --solutions--
|
|||
|
|
|
|||
|
|
```js
|
|||
|
|
// solution required
|
|||
|
|
```
|