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Terminating condition in Bubble sort is "did we swap any values during this loop"? Yes -> continue, No -> list is already sorted, exit the loop.

I don't believe that insertion/selection sort is easier to grasp. Can you type it from memory, without looking it up? Here's bubble sort:

    var swapped = true
    while swapped:
      swapped = false
      for i in 0 .. list.len-2:
        if list[i] > list[i+1]:
          swap(list[i], list[i+1])
          swapped = true




Different strokes for different folks I guess.

Selection sort was the first sorting algorithm that I ever created: Find the smallest element for slot #1. Find the next smallest for slot #2. And so on. I've recreated it from scratch many times. The double for-loop means that it is guaranteed to finish, and it is obviously O(N^2).

I did not learn about Bubble sort until my university class, where I thought, this is a terrible algorithm: It's not completely obvious that it will finish, and it's not obvious what the runtime complexity is. For example, if the inner loop used ">=" instead of ">", it would work for test data sets with unique elements, then hang forever with a real data set that contained duplicates.

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> Can you type it from memory, without looking it up?

Well, yeah, but that’s not a very useful heuristic for people who are already aware of the algorithms in question. If you ask people to come up with a way from scratch – probably without explicitly asking, in order to get better success, like by watching how they sort cards – I bet they won’t tend to come up with bubble sort. Maybe that says something about the relative intuitiveness of the approaches? Or not.

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I recall "inventing" bubble sort during one of my first CS classes when the question was posed of how to sort a list. So, not that outlandish.

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Agree. I remember the names of many of these algorithms, but not the logic.

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Let's see.

  for i in 1 .. list.len - 1:
    j = i - 1
    while j >= 0 and list[j] > list[j + 1]:
      swap(list[j], list[j + 1])
      j = j - 1

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