Commit 3be02b5

dubzzztrekhleb

authored and

committed

Fix CountingSort for negative numbers (trekhleb#100)

1 parent eec7f2f commit 3be02b5Copy full SHA for 3be02b5

File tree

2 files changed

+14

-6

lines changed

src/algorithms/sorting/counting-sort
- CountingSort.js
- __test__
  - CountingSort.test.js

2 files changed

+14

-6

lines changed

`‎src/algorithms/sorting/counting-sort/CountingSort.js‎`

Lines changed: 9 additions & 5 deletions

Original file line number	Diff line number	Diff line change
`@@ -5,8 +5,9 @@ export default class CountingSort extends Sort {`
`5`	`5`	`* @param {number[]} originalArray`
`6`	`6`	`* @param {number} [biggestElement]`
`7`	`7`	`*/`
`8`		`- sort(originalArray, biggestElement = 0) {`
	`8`	`+ sort(originalArray, smallestElement=0,biggestElement = 0) {`
`9`	`9`	`// Detect biggest element in array in order to build number bucket array later.`
	`10`	`+ let detectedSmallestElement = smallestElement;`
`10`	`11`	`let detectedBiggestElement = biggestElement;`
`11`	`12`	`if (!detectedBiggestElement) {`
`12`	`13`	`originalArray.forEach((element) => {`
`@@ -16,17 +17,20 @@ export default class CountingSort extends Sort {`
`16`	`17`	`if (this.comparator.greaterThan(element, detectedBiggestElement)) {`
`17`	`18`	`detectedBiggestElement = element;`
`18`	`19`	`}`
	`20`	`+ if (this.comparator.greaterThan(detectedSmallestElement, element)) {`
	`21`	`+ detectedSmallestElement = element;`
	`22`	`+ }`
`19`	`23`	`});`
`20`	`24`	`}`
`21`	`25`
`22`	`26`	`// Init buckets array.`
`23`	`27`	`// This array will hold frequency of each number from originalArray.`
`24`		`- const buckets = Array(detectedBiggestElement + 1).fill(0);`
	`28`	`+ const buckets = Array(detectedBiggestElement -detectedSmallestElement+ 1).fill(0);`
`25`	`29`	`originalArray.forEach((element) => {`
`26`	`30`	`// Visit element.`
`27`	`31`	`this.callbacks.visitingCallback(element);`
`28`	`32`
`29`		`- buckets[element] += 1;`
	`33`	`+ buckets[element-detectedSmallestElement] += 1;`
`30`	`34`	`});`
`31`	`35`
`32`	`36`	`// Add previous frequencies to the current one for each number in bucket`
`@@ -53,13 +57,13 @@ export default class CountingSort extends Sort {`
`53`	`57`	`this.callbacks.visitingCallback(element);`
`54`	`58`
`55`	`59`	`// Get correct position of this element in sorted array.`
`56`		`- const elementSortedPosition = buckets[element];`
	`60`	`+ const elementSortedPosition = buckets[element-detectedSmallestElement];`
`57`	`61`
`58`	`62`	`// Put element into correct position in sorted array.`
`59`	`63`	`sortedArray[elementSortedPosition] = element;`
`60`	`64`
`61`	`65`	`// Increase position of current element in the bucket for future correct placements.`
`62`		`- buckets[element] += 1;`
	`66`	`+ buckets[element-detectedSmallestElement] += 1;`
`63`	`67`	`}`
`64`	`68`
`65`	`69`	`// Return sorted array.`

`‎src/algorithms/sorting/counting-sort/test/CountingSort.test.js‎`

Lines changed: 5 additions & 1 deletion

Original file line number	Diff line number	Diff line change
`@@ -18,6 +18,10 @@ describe('CountingSort', () => {`
`18`	`18`	`SortTester.testSort(CountingSort);`
`19`	`19`	`});`
`20`	`20`
	`21`	`+ it('should sort negative numbers', () => {`
	`22`	`+ SortTester.testNegativeNumbersSort(CountingSort);`
	`23`	`+ });`
	`24`	`+`
`21`	`25`	`it('should allow to use specify maximum integer value in array to make sorting faster', () => {`
`22`	`26`	`const visitingCallback = jest.fn();`
`23`	`27`	`const sorter = new CountingSort({ visitingCallback });`
`@@ -27,7 +31,7 @@ describe('CountingSort', () => {`
`27`	`31`	`return element > accumulator ? element : accumulator;`
`28`	`32`	`}, 0);`
`29`	`33`
`30`		`- const sortedArray = sorter.sort(notSortedArr, biggestElement);`
	`34`	`+ const sortedArray = sorter.sort(notSortedArr, 0,biggestElement);`
`31`	`35`
`32`	`36`	`expect(sortedArray).toEqual(sortedArr);`
`33`	`37`	`// Normally visitingCallback is being called 60 times but in this case`

0 commit comments

Comments

(0)

Navigation Menu

Search code, repositories, users, issues, pull requests...

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

Commit 3be02b5

File tree

2 files changed

2 files changed

`‎src/algorithms/sorting/counting-sort/CountingSort.js‎`

`‎src/algorithms/sorting/counting-sort/test/CountingSort.test.js‎`

0 commit comments

File tree

2 files changed

2 files changed

‎src/algorithms/sorting/counting-sort/CountingSort.js‎

‎src/algorithms/sorting/counting-sort/__test__/CountingSort.test.js‎

0 commit comments

`‎src/algorithms/sorting/counting-sort/CountingSort.js‎`

`‎src/algorithms/sorting/counting-sort/test/CountingSort.test.js‎`