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Add more test cases for linked list reversion.

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+17

-8

lines changed

src/data-structures/linked-list
- LinkedList.js
- __test__
  - LinkedList.test.js

+17

-8

lines changed

Lines changed: 6 additions & 6 deletions

Original file line number	Diff line number	Diff line change
`@@ -243,27 +243,27 @@ export default class LinkedList {`
`243`	`243`	`}`
`244`	`244`
`245`	`245`	`/**`
`246`		`- * Reverse a singly linked list use to three variables`
`247`		`- * @returns {ReservedLinkedList}`
	`246`	`+ * Reverse a linked list.`
	`247`	`+ * @returns {LinkedList}`
`248`	`248`	`*/`
`249`	`249`	`reverse() {`
`250`	`250`	`let currNode = this.head;`
`251`	`251`	`let prevNode = null;`
`252`	`252`	`let nextNode = null;`
`253`	`253`
`254`	`254`	`while (currNode) {`
`255`		`- // Store next node`
	`255`	`+ // Store next node.`
`256`	`256`	`nextNode = currNode.next;`
`257`	`257`
`258`		`- // Change next node of the current`
	`258`	`+ // Change next node of the current node so it would link to previous node.`
`259`	`259`	`currNode.next = prevNode;`
`260`	`260`
`261`		`- // Move forward prev and current nodes one step`
	`261`	`+ // Move prevNode and currNode nodes one step forward.`
`262`	`262`	`prevNode = currNode;`
`263`	`263`	`currNode = nextNode;`
`264`	`264`	`}`
`265`	`265`
`266`		`- // Reset head, tail`
	`266`	`+ // Reset head and tail.`
`267`	`267`	`this.tail = this.head;`
`268`	`268`	`this.head = prevNode;`
`269`	`269`

Lines changed: 11 additions & 2 deletions

Original file line number	Diff line number	Diff line change
`@@ -243,15 +243,24 @@ describe('LinkedList', () => {`
`243`	`243`	`expect(() => linkedList.reverseTraversal(linkedList.head)).toThrow();`
`244`	`244`	`});`
`245`	`245`
`246`		`- it('should reverse the singly linked list', () => {`
	`246`	`+ it('should reverse linked list', () => {`
`247`	`247`	`const linkedList = new LinkedList();`
`248`	`248`
	`249`	`+ // Add test values to linked list.`
`249`	`250`	`linkedList`
`250`	`251`	`.append(1)`
`251`	`252`	`.append(2)`
`252`	`253`	`.append(3);`
`253`	`254`
`254`	`255`	`expect(linkedList.toString()).toBe('1,2,3');`
`255`		`- expect(linkedList.reverse().toString()).toBe('3,2,1');`
	`256`	`+ expect(linkedList.head.value).toBe(1);`
	`257`	`+ expect(linkedList.tail.value).toBe(3);`
	`258`	`+`
	`259`	`+ // Reverse linked list.`
	`260`	`+ linkedList.reverse();`
	`261`	`+`
	`262`	`+ expect(linkedList.toString()).toBe('3,2,1');`
	`263`	`+ expect(linkedList.head.value).toBe(3);`
	`264`	`+ expect(linkedList.tail.value).toBe(1);`
`256`	`265`	`});`
`257`	`266`	`});`

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