Add Bead Sort (aka Gravity Sort) Algorithm

DIRECTORY.md

@@ -99,6 +99,7 @@
  * [LinearSearch](https://github.com/TheAlgorithms/Javascript/blob/master/Search/LinearSearch.js)
 
 ## Sorts
+ * [BeadSort](https://github.com/TheAlgorithms/Javascript/blob/master/Sorts/BeadSort.js)
  * [BogoSort](https://github.com/TheAlgorithms/Javascript/blob/master/Sorts/BogoSort.js)
  * [BubbleSort](https://github.com/TheAlgorithms/Javascript/blob/master/Sorts/BubbleSort.js)
  * [BucketSort](https://github.com/TheAlgorithms/Javascript/blob/master/Sorts/BucketSort.js)

Sorts/BeadSort.js

@@ -0,0 +1,69 @@
+/**
+ * Bead sort (also known as Gravity sort)
+ * https://en.wikipedia.org/wiki/Bead_sort
+ *
+ * Does counting sort of provided array according to
+ * the digit represented by exp.
+ * Only works for arrays of positive integers.
+ */
+
+// > beadSort([-1, 5, 8, 4, 3, 19])
+// ! RangeError: Sequence must be a list of positive integers!
+// > beadSort([5, 4, 3, 2, 1])
+// [1, 2, 3, 4, 5]
+// > beadSort([7, 9, 4, 3, 5])
+// [3, 4, 5, 7, 9]
+
+function beadSort (sequence) {
+ // first, let's check that our sequence consists
+ // of positive integers
+ if (sequence.some((integer) => integer < 0)) {
+ throw RangeError('Sequence must be a list of positive integers!')
+ }
+
+ const sequenceLength = sequence.length
+ const max = Math.max(...sequence)
+
+ // set initial grid
+ const grid = sequence.map(number => {
+ const maxArr = new Array(max)
+
+ for (let i = 0; i < number; i++) {
+ maxArr[i] = '*'
+ }
+
+ return maxArr
+ })
+
+ // drop the beads!
+ for (let col = 0; col < max; col++) {
+ let beadsCount = 0
+
+ for (let row = 0; row < sequenceLength; row++) {
+ if (grid[row][col] === '*') {
+ beadsCount++
+ }
+ }
+
+ for (let row = sequenceLength - 1; row > -1; row--) {
+ if (beadsCount) {
+ grid[row][col] = '*'
+ beadsCount--
+ } else {
+ grid[row][col] = undefined
+ }
+ }
+ }
+
+ // and, finally, let's turn our bead rows into their respective numbers
+ const sortedSequence = grid.map((beadArray) => {
+ const beadsArray = beadArray.filter(bead => bead === '*')
+
+ return beadsArray.length
+ })
+
+ return sortedSequence
+}
+
+// implementation
+console.log(beadSort([5, 4, 3, 2, 1]))