红黑树
BBST：自平衡的二叉树
（1）根结点为黑，外部节点为黑。
（2）其余节点，若为红，则只能有黑孩子。
（3）外部节点到根结点，途中黑节点数目相等。（黑深度）
通过lifting（提升变换）等价拓扑变换，所有底层节点都变成沿同一水平高度平级的分布。可知道红黑树==（2，4）树（也叫4阶B树，每个超级节点（1～3），孩子节点（2～4））。
英语
- she's wearing more makeup than usual, especially with the bright red lipstick.
- well not everyone agrees with you.
- what's with all the makeup.
- lifespan 寿命／使用寿命
- flow 流动循环
- she felt like dressing up today, so she put on more makeup than she usually wears.
- that lipstick is like a fire engine.
- you and i are just opposites, you are always doing something new, and i would rather just relax.
- i have a romantic side, yes, but i'm practical. my man has got to be good looking, well-dressed and hopefully rich! ha hah! then that lets me out.
- pessimists see a glass as half empty rather than half full.
- to innovate means to come up with a new way of doing something.
