Disjoint Set Union (DSU)

If you're learning DSU for the first time, I recommend solving them in the following order:

1. 755C - PolandBall and Forest — my solution(381760852)
2. 217A - Ice Skating — my solution(381800055)
3. 445B - DZY Loves Chemistry — my solution(382353172)
4. 1263D - Secret Passwords — my solution(381810414)
5. 939D - Love Rescue — my solution(381830505)
6. 1012B - Chemical table — my solution(384865311)
7. 1167C - News Distribution — my solution(388674692)
8. 1249B1 - Books Exchange (easy version) — my solution(382086807)
9. 893C - Rumor — my solution(394841571)
10. 277A - Learning Languages
11. 25D - Roads not only in Berland — my solution(382417740)
12. 1609D - Social Network — my solution(382447487)
13. 1559D1 - Mocha and Diana (Easy Version)
14. 1559D2 - Mocha and Diana (Hard Version)
15. 292D - Connected Components
16. 891C - Envy
17. 1618G - Trader Problem
18. 920E - Connected Components?

Remaining answer i will add shortly.

Tip: Don't solve these problems by simply memorizing the DSU template. Before coding, always ask yourself:

• What do the sets represent?
• When should two sets be merged?
• What does the representative of a set signify?

Once you can answer these questions, identifying DSU in future graph problems becomes much easier.