世界上最好和最美丽的东西是看不见甚至摸不着的 - 它们必须用心去感受。
"The best and most beautiful things in the world cannot be seen or even touched - they must be felt with the heart."
"A book can be more dangerous than a knife in the right hands."
The concept of NP-completeness has provided a powerful tool for understanding the complexity of problems.
Anything you say before the word “but” does not count.