ee1e8abd87
* feat(tools): add seed/solution restore script * chore(curriculum): remove empty sections' markers * chore(curriculum): add seed + solution to Chinese * chore: remove old formatter * fix: update getChallenges parse translated challenges separately, without reference to the source * chore(curriculum): add dashedName to English * chore(curriculum): add dashedName to Chinese * refactor: remove unused challenge property 'name' * fix: relax dashedName requirement * fix: stray tag Remove stray `pre` tag from challenge file. Signed-off-by: nhcarrigan <nhcarrigan@gmail.com> Co-authored-by: nhcarrigan <nhcarrigan@gmail.com>
88 lines
2.2 KiB
Markdown
88 lines
2.2 KiB
Markdown
---
|
|
id: 5951ed8945deab770972ae56
|
|
title: Towers of Hanoi
|
|
challengeType: 5
|
|
forumTopicId: 302341
|
|
dashedName: towers-of-hanoi
|
|
---
|
|
|
|
# --description--
|
|
|
|
Solve the [Towers of Hanoi](https://en.wikipedia.org/wiki/Towers_of_Hanoi "wp: Towers_of_Hanoi") problem.
|
|
|
|
Your solution should accept the number of discs as the first parameters, and three string used to identify each of the three stacks of discs, for example `towerOfHanoi(4, 'A', 'B', 'C')`. The function should return an array of arrays containing the list of moves, source -> destination.
|
|
|
|
For example, the array `[['A', 'C'], ['B', 'A']]` indicates that the 1st move was to move a disc from stack A to C, and the 2nd move was to move a disc from stack B to A.
|
|
|
|
<p></p>
|
|
|
|
# --hints--
|
|
|
|
`towerOfHanoi` should be a function.
|
|
|
|
```js
|
|
assert(typeof towerOfHanoi === 'function');
|
|
```
|
|
|
|
`towerOfHanoi(3, ...)` should return 7 moves.
|
|
|
|
```js
|
|
assert(res3.length === 7);
|
|
```
|
|
|
|
`towerOfHanoi(3, 'A', 'B', 'C')` should return `[['A','B'], ['A','C'], ['B','C'], ['A','B'], ['C','A'], ['C','B'], ['A','B']]`.
|
|
|
|
```js
|
|
assert.deepEqual(towerOfHanoi(3, 'A', 'B', 'C'), res3Moves);
|
|
```
|
|
|
|
`towerOfHanoi(5, "X", "Y", "Z")` 10th move should be Y -> X.
|
|
|
|
```js
|
|
assert.deepEqual(res5[9], ['Y', 'X']);
|
|
```
|
|
|
|
`towerOfHanoi(7, 'A', 'B', 'C')` first ten moves should be `[['A','B'], ['A','C'], ['B','C'], ['A','B'], ['C','A'], ['C','B'], ['A','B'], ['A','C'], ['B','C'], ['B','A']]`
|
|
|
|
```js
|
|
assert.deepEqual(towerOfHanoi(7, 'A', 'B', 'C').slice(0, 10), res7First10Moves);
|
|
```
|
|
|
|
# --seed--
|
|
|
|
## --after-user-code--
|
|
|
|
```js
|
|
const res3 = towerOfHanoi(3, 'A', 'B', 'C');
|
|
const res3Moves = [['A', 'B'], ['A', 'C'], ['B', 'C'], ['A', 'B'], ['C', 'A'], ['C', 'B'], ['A', 'B']];
|
|
const res5 = towerOfHanoi(5, 'X', 'Y', 'Z');
|
|
const res7First10Moves = [['A', 'B'], ['A', 'C'], ['B', 'C'], ['A', 'B'], ['C', 'A'], ['C', 'B'], ['A', 'B'], ['A', 'C'], ['B', 'C'], ['B', 'A']];
|
|
```
|
|
|
|
## --seed-contents--
|
|
|
|
```js
|
|
function towerOfHanoi(n, a, b, c) {
|
|
|
|
return [[]];
|
|
}
|
|
```
|
|
|
|
# --solutions--
|
|
|
|
```js
|
|
function towerOfHanoi(n, a, b, c) {
|
|
const res = [];
|
|
towerOfHanoiHelper(n, a, c, b, res);
|
|
return res;
|
|
}
|
|
|
|
function towerOfHanoiHelper(n, a, b, c, res) {
|
|
if (n > 0) {
|
|
towerOfHanoiHelper(n - 1, a, c, b, res);
|
|
res.push([a, c]);
|
|
towerOfHanoiHelper(n - 1, b, a, c, res);
|
|
}
|
|
}
|
|
```
|