# Substitution Cipher

### From Progteam

(Difference between revisions)

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*If graph has a cycle, or is disconnected, you can't do it | *If graph has a cycle, or is disconnected, you can't do it | ||

*Else, it's a connected DAG. | *Else, it's a connected DAG. | ||

- | *Topological. | + | *Topological sort. Boom. |

{{problem-stub}} | {{problem-stub}} | ||

[[Sorting]] | [[Sorting]] |

## Revision as of 22:56, 16 June 2008

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 sort. Boom.