Bubble Sort

Stats

Worst Case Performance: O(n²)

Best Case Performance: O(n)

Optimized Psuedocode

Bubble Sort can be optimized by observing that the n-th pass finds the n-th largest element and puts it into its final place. So the inner loop can avoid looking at the last n-1 items when running for the n-th time.

function bubbleSort(items) {
  n = count(items);
  swapped = false;
  while(!swapped) {
    swapped = false;
    for(i = 1; i < n; i++) {
      if(items[i-1] > items[i]) {
        tmp = items[i-1];
        items[i-1] = items[i];
        items[i] = tmp;
        swapped = true;
      }
    }
    n = n-1;
  }
}

Unoptimized Psuedocode

function bubbleSort(items) {
  swapped = false;
  while(!swapped) {
    swapped = false;
    for(i = 1; i < count(items); i++) {
      if(items[i-1] > items[i]) {
        tmp = items[i-1];
        items[i-1] = items[i];
        items[i] = tmp;
        swapped = true;
      }
    }
  }
}

Additional Info

Wikipedia Article: [http://en.wikipedia.org/wiki/Bubble_sort]