---
categories: Graph theory
---

## Problems
- [DZY Loves Planting](http://codeforces.com/contest/444/problem/E)
- [Ringworld](https://open.kattis.com/problems/ringworld)
- [Teams](http://www.ioinformatics.org/locations/ioi15/contest/day1/teams-en.pdf) [^1]

## See also
- [Bipartite matching]()
- [Latin squares]()

## External links
- [Hall's marriage theorem](https://en.wikipedia.org/wiki/Hall%27s_marriage_theorem)


[^1]: <http://www.ioinformatics.org/locations/ioi15/contest/solutions/teams.pdf>