1 |
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2 | export class QueueNode {
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3 | constructor () {
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4 | |
5 |
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6 |
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7 | this.next = null
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8 | }
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9 | }
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10 |
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11 | export class Queue {
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12 | constructor () {
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13 | |
14 |
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15 |
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16 | this.start = null
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17 | |
18 |
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19 |
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20 | this.end = null
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21 | }
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22 | }
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23 |
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24 |
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25 |
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26 |
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27 |
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28 |
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29 |
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30 | export const create = () => new Queue()
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31 |
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32 |
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33 |
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34 |
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35 | export const isEmpty = queue => queue.start === null
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36 |
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37 |
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38 |
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39 |
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40 |
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41 | export const enqueue = (queue, n) => {
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42 | if (queue.end !== null) {
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43 | queue.end.next = n
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44 | queue.end = n
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45 | } else {
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46 | queue.end = n
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47 | queue.start = n
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48 | }
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49 | }
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50 |
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51 |
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52 |
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53 |
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54 |
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55 | export const dequeue = queue => {
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56 | const n = queue.start
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57 | if (n !== null) {
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58 |
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59 | queue.start = n.next
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60 | if (queue.start === null) {
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61 | queue.end = null
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62 | }
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63 | return n
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64 | }
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65 | return null
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66 | }
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