2.2 KiB
id | title | challengeType | forumTopicId | dashedName |
---|---|---|---|---|
5951ed8945deab770972ae56 | Towers of Hanoi | 5 | 302341 | towers-of-hanoi |
--description--
Solve the Towers of Hanoi problem. The number of objects will be given as the first parameter, followed by the strings used to identify each stack of objects. Create a nested array containing the list of moves, ["source", "destination"]
.
For example, the parameters (4, 'A', 'B', 'C')
, will result in nested array of moves [['A', 'C'], ['B', 'A']]
, indicating that the 1st move was to move an object from stack A
to C
and the 2nd move was to move an object from stack B
to A
.
--instructions--
Write a function that returns the moves to stack the objects in a nested array.
--hints--
towerOfHanoi
should be a function.
assert(typeof towerOfHanoi === 'function');
towerOfHanoi(3, ...)
should return 7 moves.
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']]
.
assert.deepEqual(towerOfHanoi(3, 'A', 'B', 'C'), res3Moves);
towerOfHanoi(5, "X", "Y", "Z")
10th move should be Y -> X.
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']]
assert.deepEqual(towerOfHanoi(7, 'A', 'B', 'C').slice(0, 10), res7First10Moves);
--seed--
--after-user-code--
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--
function towerOfHanoi(n, a, b, c) {
return [[]];
}
--solutions--
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);
}
}