Divide and Conquer 常见技巧

与Dynamic Programming结合非常多。

1. Chap3. Dynamic Programming state .
2. Brute Force if can't prune.
   1. add binary operator
3. 区别对待special case. 非常经典的划分.
   • tournament tree to find second minimum.
4. Bottom-Up in Tree实际上就是传回每一个subproblem的之间互相计算需要传递的值。比DP 的state推断更加直观