README

Skyline Sort is a sorting algorithm with minimal time complexity, simple implementation, and high efficiency with dense source data.

Although Skyline benefits from a couple JavaScript-specific features, it is possible to implement it in other languages as well with only a bit of tweaking.

Advantages

1. Time complexity of O(n)
2. Excels at processing data sets with many duplicates
3. Easy, concise implementation
4. Not technically unstable since only raw numbers can be processed (currently)

Disadvantages

1. Implementations in certain languages may require too much memory when processing sparse data sets

The code

function skyline(a) {
  var b=[],c=0,i,j
  for(i of a)b[i]=~~b[i]+1
  for(i in b)for(;b[i]--;)a[c++]=i*1
  return a
}

How it works

//Function is passed an array of integers
function skyline(a) {

  //Declare temporary array, counter, and two indexes
  //a and b are arrays, c is a counter, i and j are indexes
  var b=[],c=0,i,j

  //Enumerate over original array
  //If b has no index of i, create it; if it does, add 1 to the value
  for(i of a)b[i]=~~b[i]+1

  //Enumerate over the temporary array. Copy over each index the number of times indicated by its value
  for(i in b)for(;b[i]--;)a[c++]=i*1

  //Array is sorted. Done.
  return a;
}

NPM Usage

npm i skyline-sort

In your JavaScript file:

var skyline = require('skyline-sort');

Note that the NPM version contains an input validation mechanism.

module.exports = function (a) {
  var b=[],c=0,i,j,z;

  //This part right here. z declared above
  if(!Array.isArray(a)) throw "Parameter is not an array."
  for(z in a) if((a[z] == null) || (typeof a[z] == 'undefined') || isNaN(a[z])) throw `Array contains non-number ${a[z]} at position ${z}`;

  for(i of a)b[i]=~~b[i]+1
  for(i in b)for(;b[i]--;)a[c++]=i*1
  return a
}