# Substitution Cipher

### From Progteam

Sorter: | hjfreyer |
---|---|

Source: | Unknown |

Link: | http://acm.pku.edu.cn/JudgeOnline/problem?id=1506 |

**Substitution Cipher** is problem number 1506 on the Peking University ACM
site.

Solution:

- Turn the input into a list of "e<b" style rules.
- Construct a graph from these rules.
- If graph has a cycle, or is disconnected, you can't do it
- Else, it's a connected DAG.
- Topological.