回溯法

回溯法是生成一个组合的所有子集或者子系统的方法。

回溯法例子：

1. binary strings of n bits

2. subsets of a given set E of n elements

3. directed graphs of n nodes

4. undirected graphs of n nodes

5. permutations of a given size n

6. Hamiltonian cycles of a given graph

7. K-cliques of a given graph

8. K-coloring of a given graph