diff --git a/DIRECTORY.md b/DIRECTORY.md index dee2d724ce..32efef4451 100644 --- a/DIRECTORY.md +++ b/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) diff --git a/Sorts/BeadSort.js b/Sorts/BeadSort.js new file mode 100644 index 0000000000..1261fd554b --- /dev/null +++ b/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]))