Union Find
Here are the articles in this section:
128 Longest Consecutive Sequence
130 Surrounded Regions
200 Number of Islands
261 Graph Valid Tree
305 Number of Islands II
323 Number of Connected Components in an Undirected Graph
547 Friend Circles
684 Redundant Connection
685 Redundant Connection II
695 Max Area of Island
721 Accounts Merge
737 Sentence Similarity II
765 Couples Holding Hands
803 Bricks Falling When Hit