Cocktail Shaker Sort

pseudocode

cocktailSort(a):
  start = 0; end = n - 1; swapped = true
  while swapped:
    // Pass 1 (L->R): bubble largest value to end
    for i = start to end-1: if a[i] > a[i+1] swap
    end-- // lock rightmost element
    // Pass 2 (R->L): sink smallest value to start
    for i = end-1 down to start: if a[i] > a[i+1] swap
    start++ // lock leftmost element