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https://github.moeyy.xyz/https://github.com/trekhleb/javascript-algorithms.git
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Add Queue.
This commit is contained in:
parent
55d6aa5758
commit
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@ -6,6 +6,7 @@
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- [Linked List](https://github.com/trekhleb/javascript-algorithms/tree/master/src/data-structures/linked-list)
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- [Linked List](https://github.com/trekhleb/javascript-algorithms/tree/master/src/data-structures/linked-list)
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- [Hash Table](https://github.com/trekhleb/javascript-algorithms/tree/master/src/data-structures/hash-table)
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- [Hash Table](https://github.com/trekhleb/javascript-algorithms/tree/master/src/data-structures/hash-table)
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- [Queue](https://github.com/trekhleb/javascript-algorithms/tree/master/src/data-structures/queue)
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## Running Tests
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## Running Tests
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3855
package-lock.json
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3855
package-lock.json
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@ -29,5 +29,8 @@
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"eslint-plugin-jsx-a11y": "^6.0.3",
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"eslint-plugin-jsx-a11y": "^6.0.3",
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"eslint-plugin-react": "^7.7.0",
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"eslint-plugin-react": "^7.7.0",
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"jest": "^22.4.3"
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"jest": "^22.4.3"
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},
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"dependencies": {
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"npm": "^5.8.0"
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}
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}
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}
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}
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@ -3,28 +3,7 @@ import LinkedListNode from './LinkedListNode';
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export default class LinkedList {
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export default class LinkedList {
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constructor() {
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constructor() {
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this.head = null;
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this.head = null;
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}
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this.tail = null;
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append({ value, key = null }) {
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const newNode = new LinkedListNode({ value, key });
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// If there is no head yet let's make new node a head.
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if (!this.head) {
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this.head = newNode;
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return newNode;
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}
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// Rewind to last node.
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let currentNode = this.head;
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while (currentNode.next !== null) {
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currentNode = currentNode.next;
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}
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// Attach new node to the end of linked list.
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currentNode.next = newNode;
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return newNode;
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}
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}
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prepend({ value, key = null }) {
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prepend({ value, key = null }) {
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@ -36,12 +15,31 @@ export default class LinkedList {
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return newNode;
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return newNode;
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}
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}
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append({ value, key = null }) {
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const newNode = new LinkedListNode({ value, key });
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// If there is no head yet let's make new node a head.
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if (!this.head) {
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this.head = newNode;
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this.tail = newNode;
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return newNode;
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}
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// Attach new node to the end of linked list.
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this.tail.next = newNode;
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this.tail = newNode;
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return newNode;
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}
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appendUnique({ value, key = null }) {
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appendUnique({ value, key = null }) {
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const newNode = new LinkedListNode({ value, key });
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const newNode = new LinkedListNode({ value, key });
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// If there is no head yet let's make new node a head.
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// If there is no head yet let's make new node a head.
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if (!this.head) {
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if (!this.head) {
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this.head = newNode;
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this.head = newNode;
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this.tail = newNode;
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return newNode;
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return newNode;
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}
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}
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@ -66,6 +64,7 @@ export default class LinkedList {
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// Attach new node to the end of linked list.
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// Attach new node to the end of linked list.
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currentNode.next = newNode;
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currentNode.next = newNode;
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this.tail = newNode;
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return newNode;
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return newNode;
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}
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}
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@ -90,8 +89,14 @@ export default class LinkedList {
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if (currentNode.next.value === value) {
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if (currentNode.next.value === value) {
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deletedNode = currentNode.next;
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deletedNode = currentNode.next;
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currentNode.next = currentNode.next.next;
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currentNode.next = currentNode.next.next;
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} else {
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currentNode = currentNode.next;
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}
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}
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currentNode = currentNode.next;
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}
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// Check if tail must be deleted.
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if (this.tail.value === value) {
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this.tail = currentNode;
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}
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}
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return deletedNode;
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return deletedNode;
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@ -117,13 +122,44 @@ export default class LinkedList {
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if (currentNode.next.key === key) {
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if (currentNode.next.key === key) {
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deletedNode = currentNode.next;
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deletedNode = currentNode.next;
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currentNode.next = currentNode.next.next;
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currentNode.next = currentNode.next.next;
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} else {
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currentNode = currentNode.next;
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}
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}
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currentNode = currentNode.next;
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}
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// Check if tail must be deleted.
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if (this.tail.key === key) {
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this.tail = currentNode;
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}
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}
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return deletedNode;
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return deletedNode;
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}
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}
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deleteTail() {
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if (this.head === this.tail) {
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const deletedTail = this.tail;
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this.head = null;
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this.tail = null;
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return deletedTail;
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}
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const deletedTail = this.tail;
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// Rewind to the last node and delete "next" link for the node before the last one.
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let currentNode = this.head;
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while (currentNode.next) {
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if (!currentNode.next.next) {
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currentNode.next = null;
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} else {
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currentNode = currentNode.next;
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}
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}
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this.tail = currentNode;
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return deletedTail;
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}
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findByKey(key) {
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findByKey(key) {
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let currentNode = this.head;
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let currentNode = this.head;
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@ -9,6 +9,9 @@ describe('LinkedList', () => {
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it('should append node to linked list', () => {
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it('should append node to linked list', () => {
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const linkedList = new LinkedList();
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const linkedList = new LinkedList();
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expect(linkedList.head).toBeNull();
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expect(linkedList.tail).toBeNull();
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const node1 = linkedList.append({ value: 1 });
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const node1 = linkedList.append({ value: 1 });
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const node2 = linkedList.append({ value: 2, key: 'test' });
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const node2 = linkedList.append({ value: 2, key: 'test' });
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expect(node2.value).toBe(2);
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expect(node2.value).toBe(2);
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expect(node2.key).toBe('test');
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expect(node2.key).toBe('test');
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expect(linkedList.head.toString()).toBe('1');
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expect(linkedList.tail.toString()).toBe('test:2');
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expect(linkedList.toString()).toBe('1,test:2');
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expect(linkedList.toString()).toBe('1,test:2');
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});
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});
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expect(node1.value).toBe(1);
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expect(node1.value).toBe(1);
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expect(node2.value).toBe(2);
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expect(node2.value).toBe(2);
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expect(linkedList.head.toString()).toBe('2');
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expect(linkedList.tail.toString()).toBe('1');
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expect(linkedList.toString()).toBe('2,1');
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expect(linkedList.toString()).toBe('2,1');
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});
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});
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linkedList.append({ value: 2 });
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linkedList.append({ value: 2 });
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linkedList.append({ value: 3 });
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linkedList.append({ value: 3 });
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linkedList.append({ value: 3 });
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linkedList.append({ value: 3 });
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linkedList.append({ value: 3 });
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linkedList.append({ value: 4 });
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linkedList.append({ value: 4 });
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linkedList.append({ value: 5 });
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linkedList.append({ value: 5 });
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expect(linkedList.head.toString()).toBe('1');
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expect(linkedList.tail.toString()).toBe('5');
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const deletedNode = linkedList.deleteByValue(3);
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const deletedNode = linkedList.deleteByValue(3);
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expect(deletedNode.value).toBe(3);
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expect(deletedNode.value).toBe(3);
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expect(linkedList.toString()).toBe('1,2,3,4,5');
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expect(linkedList.toString()).toBe('1,2,4,5');
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linkedList.deleteByValue(3);
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linkedList.deleteByValue(3);
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expect(linkedList.toString()).toBe('1,2,4,5');
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expect(linkedList.toString()).toBe('1,2,4,5');
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linkedList.deleteByValue(1);
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linkedList.deleteByValue(1);
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expect(linkedList.toString()).toBe('2,4,5');
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expect(linkedList.toString()).toBe('2,4,5');
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expect(linkedList.head.toString()).toBe('2');
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expect(linkedList.tail.toString()).toBe('5');
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linkedList.deleteByValue(5);
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expect(linkedList.toString()).toBe('2,4');
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expect(linkedList.head.toString()).toBe('2');
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expect(linkedList.tail.toString()).toBe('4');
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linkedList.deleteByValue(4);
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expect(linkedList.toString()).toBe('2');
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expect(linkedList.head.toString()).toBe('2');
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expect(linkedList.tail.toString()).toBe('2');
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});
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it('should delete linked list tail', () => {
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const linkedList = new LinkedList();
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linkedList.append({ value: 1 });
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linkedList.append({ value: 2 });
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expect(linkedList.head.toString()).toBe('1');
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expect(linkedList.tail.toString()).toBe('2');
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const deletedNode1 = linkedList.deleteTail();
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expect(deletedNode1.value).toBe(2);
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expect(linkedList.toString()).toBe('1');
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expect(linkedList.head.toString()).toBe('1');
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expect(linkedList.tail.toString()).toBe('1');
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const deletedNode2 = linkedList.deleteTail();
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expect(deletedNode2.value).toBe(1);
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expect(linkedList.toString()).toBe('');
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expect(linkedList.head).toBeNull();
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expect(linkedList.tail).toBeNull();
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});
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});
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it('should delete node by key from linked list', () => {
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it('should delete node by key from linked list', () => {
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28
src/data-structures/queue/Queue.js
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28
src/data-structures/queue/Queue.js
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import LinkedList from '../linked-list/LinkedList';
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export default class Queue {
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constructor() {
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this.linkedList = new LinkedList();
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}
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isEmpty() {
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return !this.linkedList.tail;
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}
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peek() {
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if (!this.linkedList.tail) {
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return null;
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}
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return this.linkedList.tail.value;
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}
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add(value) {
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this.linkedList.append({ value });
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}
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remove() {
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const removedTail = this.linkedList.deleteTail();
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return removedTail ? removedTail.value : null;
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}
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}
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8
src/data-structures/queue/README.md
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8
src/data-structures/queue/README.md
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# Queue
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|Operation |Complexity |
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|---------------------------|-------------------|
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|Find |O() |
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|Insert/delete at beginning |O() |
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|Insert/delete in middle |O() |
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|Insert/delete at end |O() |
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51
src/data-structures/queue/__test__/Queue.test.js
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51
src/data-structures/queue/__test__/Queue.test.js
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import Queue from '../Queue';
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describe('Queue', () => {
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it('should create empty queue', () => {
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const queue = new Queue();
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expect(queue).not.toBeNull();
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expect(queue.linkedList).not.toBeNull();
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});
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it('should add data to queue', () => {
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const queue = new Queue();
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queue.add(1);
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queue.add(2);
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expect(queue.linkedList.toString()).toBe('1,2');
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});
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it('should peek data from queue', () => {
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const queue = new Queue();
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expect(queue.peek()).toBeNull();
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queue.add(1);
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queue.add(2);
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expect(queue.peek()).toBe(2);
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expect(queue.peek()).toBe(2);
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});
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it('should check if queue is empty', () => {
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const queue = new Queue();
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expect(queue.isEmpty()).toBeTruthy();
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queue.add(1);
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expect(queue.isEmpty()).toBeFalsy();
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});
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it('should remove from empty', () => {
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const queue = new Queue();
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queue.add(1);
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queue.add(2);
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expect(queue.remove()).toBe(2);
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expect(queue.remove()).toBe(1);
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expect(queue.isEmpty()).toBeTruthy();
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});
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});
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Reference in New Issue
Block a user