Notes for [1, 2] (Partially)

The purpose of the notes series Good Algorithms, especially for those natural problems, should be simple and elegant. Natural problems are those with universal assumptions, and search for a solution with symmetric properties. However, in the real world, things are not perfect; problems are often skewed. And the biggest obstacle is, things are often difficult. People believe that randomization and approximation may come to rescue, and then, algorithms become even more erratic. Honestly, randomization and approximation themselves are inherently symmetric, and algorithms could still be simple, effective and beautiful. But like the play of Go 1, they might not still be the best. However, most of us still prefer a move in Go with massiness and resulting in sound shape, even if it could not bring us the maximum benefits. And sim-ple, elegant algorithms are still be thought the most valuable treasure computer scientists bring to the human beings