【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
【721】Accounts Merge
【737】Sentence Similarity II
【765】Couples Holding Hands
【778】Swim in Rising Water
【803】Bricks Falling When Hit
【839】Similar String Groups
【928】Minimize Malware Spread II
【LeetCode】并查集 union-find（共16题）
原文：https://www.cnblogs.com/zhangwanying/p/9964303.html