He came to give a lecture at UT Austin, where I did my undergrad. I had a chance to ask him a question: "what's the story behind inventing QuickSort?". He said something simple, like "first I thought of MergeSort, and then I thought of QuickSort" - as if it were just natural thought. He came across as a kind and humble person. Glad to have met one of the greats of the field!

Happy to meet you. I was there and I remember that question being asked. I think it was 2010.

If I remember correctly he had two immediate ideas, his first was bubble sort, the second turned out to be quicksort.

He was already very frail by then. Yet clarity of mind was undiminished. What came across in that talk, in addition to his technical material, was his humor and warmth.

I remember this vividly! I believe he said that he thought of _Bubble Sort_ first, but that it was too slow, so he came up with QuickSort next

He discusses this and his sixpence wager here: https://youtu.be/pJgKYn0lcno

(Source: TFA)

Haha I was there too. I remember he made thinking clearly seem so simple. What a humble man.

If I remember correctly, his talk was about how the world of science-the pure pursuit of truth-and the world of engineering-the practical application of solutions under constraints-had to learn from each other.