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]))