counting-sort.js

// Implement counting sort algorithm
// Complexity O(n+k) 
// let toNum = (ch) => ch.charCodeAt(0); 
// let toChar = (num) => String.fromCharCode(num); 
// const RANGE = 255; // numbers, letters

let countingSort = function(input)
{
  
  let inter = [];
  let output = [];

  input.map(i => {
    inter[i] = inter[i] ? inter[i]+1 : 1;
  });
   
  inter.map((i, ind) => {
    for(let k=0; k<i; k++) {
      output.push(ind);
    }
  })
  
  return output;
}

console.log(countingSort([4, 7, 7, 2, 8, 1, 9]));