BucketSort.js

/**
 * BucketSort implementation.
 *
 * Wikipedia says: Bucket sort, or bin sort, is a sorting algorithm that works by distributing the elements of an array
 * into a number of buckets. Each bucket is then sorted individually, either using a different sorting algorithm, or by
 * recursively applying the bucket sorting algorithm. It is a distribution sort, and is a cousin of radix sort in the
 * most to least significant digit flavour. Bucket sort is a generalization of pigeonhole sort. Bucket sort can be
 * implemented with comparisons and therefore can also be considered a comparison sort algorithm. The computational
 * complexity estimates involve the number of buckets.
 *
 * @see https://en.wikipedia.org/wiki/Bucket_sort#:~:text=Bucket%20sort%2C%20or%20bin%20sort,applying%20the%20bucket%20sorting%20algorithm.&text=Sort%20each%20non%2Dempty%20bucket.
 *
 * Time Complexity of Solution:
 * Best Case O(n); Average Case O(n); Worst Case O(n)
 *
 * @param {number[]} list The array of numbers to be sorted.
 * @param {number} size The size of the buckets used. If not provided, size will be 5.
 * @return {number[]} An array of numbers sorted in increasing order.
 */
export function bucketSort(list, size) {
 if (undefined === size) {
 size = 5
 }
 if (list.length === 0) {
 return list
 }
 let min = list[0]
 let max = list[0]
 // find min and max
 for (let iList = 0; iList < list.length; iList++) {
 if (list[iList] < min) {
 min = list[iList]
 } else if (list[iList] > max) {
 max = list[iList]
 }
 }
 // how many buckets we need
 const count = Math.floor((max - min) / size) + 1

 // create buckets
 const buckets = []
 for (let iCount = 0; iCount < count; iCount++) {
 buckets.push([])
 }

 // bucket fill
 for (let iBucket = 0; iBucket < list.length; iBucket++) {
 const key = Math.floor((list[iBucket] - min) / size)
 buckets[key].push(list[iBucket])
 }
 const sorted = []
 // now sort every bucket and merge it to the sorted list
 for (let iBucket = 0; iBucket < buckets.length; iBucket++) {
 const arr = buckets[iBucket].sort((a, b) => a - b)
 for (let iSorted = 0; iSorted < arr.length; iSorted++) {
 sorted.push(arr[iSorted])
 }
 }
 return sorted
}