quicksort algorithms

quicksort.hs

quicksort (p:xs) = (quicksort lesser) ++ [p] ++ (quicksort greater)
    where
        lesser = filter (< p) xs         
        greater = filter (>= p) xs
 
main = do print(quicksort [4,3,2,1])

quicksort.js

function quicksort(arr) {
    if (arr.length < 2) {
        return arr;
    } else {
        var pivot = arr[0];
        var less = [];
        var greater = [];
        var result = [];
 
        for (var i = 1; i < arr.length; i++) { //skip first array
            var j = arr[i];
            if (j <= pivot) {                           
                less.push(j);
            } else if (j > pivot) {
                greater.push(j);
            }
        }
 
        return quicksort(less) + [pivot] + quicksort(greater);
    }
}
 
console.log(quicksort([10,5,2,3,7,4]));

quicksort.py

def quicksort(array):
    # print(array)
    if len(array) < 2:
        return array #Base case: arrays with 0 or 1 element are already “sorted.”
    else:
        pivot = array[0] #Recursive case
        less = [i for i in array[1:] if i <= pivot] #Sub-array of all the elements less than the pivot       
        greater = [i for i in array[1:] if i > pivot] #Sub-array of all the elements greater than the pivot
        # print (less)
        # print (greater)
        result = quicksort(less) + [pivot] + quicksort(greater)
        print(result)
        return result
 
print (quicksort([10, 10,5, 2, 3]))