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Add Tower of Hanoi.

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Oleksii Trekhleb 2018-05-14 11:28:56 +03:00
parent 8c102a3f62
commit f8222ed397
2 changed files with 51 additions and 41 deletions
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56
src/algorithms/uncategorized/hanoi-tower/__test__/hanoiTower.test.js
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@ -1,42 +1,62 @@
import hanoiTower from '../hanoiTower';
import Stack from '../../../../data-structures/stack/Stack';
describe('hanoiTower', () => {
it('should solve tower of hanoi puzzle with 2 discs', () => {
const moveCallbackMock = jest.fn();
const moveCallback = jest.fn();
const numberOfDiscs = 2;
hanoiTower(numberOfDiscs, moveCallbackMock);
const fromPole = new Stack();
const withPole = new Stack();
const toPole = new Stack();
expect(moveCallbackMock).toHaveBeenCalledTimes((2 ** numberOfDiscs) - 1);
hanoiTower({
numberOfDiscs,
moveCallback,
fromPole,
withPole,
toPole,
});
expect(moveCallbackMock.mock.calls[0][0]).toBe(1);
expect(moveCallbackMock.mock.calls[0][1]).toEqual([1, 2]);
expect(moveCallbackMock.mock.calls[0][2]).toEqual([]);
expect(moveCallback).toHaveBeenCalledTimes((2 ** numberOfDiscs) - 1);
expect(moveCallbackMock.mock.calls[1][0]).toBe(2);
expect(moveCallbackMock.mock.calls[1][1]).toEqual([2]);
expect(moveCallbackMock.mock.calls[1][2]).toEqual([]);
expect(fromPole.toArray()).toEqual([]);
expect(toPole.toArray()).toEqual([1, 2]);
expect(moveCallbackMock.mock.calls[2][0]).toBe(1);
expect(moveCallbackMock.mock.calls[2][1]).toEqual([1]);
expect(moveCallbackMock.mock.calls[2][2]).toEqual([2]);
expect(moveCallback.mock.calls[0][0]).toBe(1);
expect(moveCallback.mock.calls[0][1]).toEqual([1, 2]);
expect(moveCallback.mock.calls[0][2]).toEqual([]);
expect(moveCallback.mock.calls[1][0]).toBe(2);
expect(moveCallback.mock.calls[1][1]).toEqual([2]);
expect(moveCallback.mock.calls[1][2]).toEqual([]);
expect(moveCallback.mock.calls[2][0]).toBe(1);
expect(moveCallback.mock.calls[2][1]).toEqual([1]);
expect(moveCallback.mock.calls[2][2]).toEqual([2]);
});
it('should solve tower of hanoi puzzle with 3 discs', () => {
const moveCallbackMock = jest.fn();
const moveCallback = jest.fn();
const numberOfDiscs = 3;
hanoiTower(numberOfDiscs, moveCallbackMock);
hanoiTower({
numberOfDiscs,
moveCallback,
});
expect(moveCallbackMock).toHaveBeenCalledTimes((2 ** numberOfDiscs) - 1);
expect(moveCallback).toHaveBeenCalledTimes((2 ** numberOfDiscs) - 1);
});
it('should solve tower of hanoi puzzle with 6 discs', () => {
const moveCallbackMock = jest.fn();
const moveCallback = jest.fn();
const numberOfDiscs = 6;
hanoiTower(numberOfDiscs, moveCallbackMock);
hanoiTower({
numberOfDiscs,
moveCallback,
});
expect(moveCallbackMock).toHaveBeenCalledTimes((2 ** numberOfDiscs) - 1);
expect(moveCallback).toHaveBeenCalledTimes((2 ** numberOfDiscs) - 1);
});
});

36
src/algorithms/uncategorized/hanoi-tower/hanoiTower.js
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@ -1,17 +1,5 @@
import Stack from '../../../data-structures/stack/Stack';
/**
* @param {Stack} fromPole
* @param {Stack} toPole
* @param {function(disc: number, fromPole: number[], toPole: number[])} moveCallback
*/
function moveDisc(fromPole, toPole, moveCallback) {
moveCallback(fromPole.peek(), fromPole.toArray(), toPole.toArray());
const disc = fromPole.pop();
toPole.push(disc);
}
/**
* @param {number} numberOfDiscs
* @param {Stack} fromPole
@ -28,7 +16,9 @@ function hanoiTowerRecursive({
}) {
if (numberOfDiscs === 1) {
// Base case with just one disc.
moveDisc(fromPole, toPole, moveCallback);
moveCallback(fromPole.peek(), fromPole.toArray(), toPole.toArray());
const disc = fromPole.pop();
toPole.push(disc);
} else {
// In case if there are more discs then move them recursively.
@ -64,21 +54,21 @@ function hanoiTowerRecursive({
/**
* @param {number} numberOfDiscs
* @param {function(disc: number, fromPole: number[], toPole: number[])} moveCallback
* @param {Stack} [fromPole]
* @param {Stack} [withPole]
* @param {Stack} [toPole]
*/
export default function hanoiTower(numberOfDiscs, moveCallback) {
export default function hanoiTower({
numberOfDiscs,
moveCallback,
fromPole = new Stack(),
withPole = new Stack(),
toPole = new Stack(),
}) {
// Each of three poles of Tower of Hanoi puzzle is represented as a stack
// that might contain elements (discs). Each disc is represented as a number.
// Larger discs have bigger number equivalent.
// The pole from where the discs should be moved.
const fromPole = new Stack();
// The middle pole that should be used as a helper.
const withPole = new Stack();
// The destination pole where all discs need to be moved.
const toPole = new Stack();
// Let's create the discs and put them to the fromPole.
for (let discSize = numberOfDiscs; discSize > 0; discSize -= 1) {
fromPole.push(discSize);