%%time

js = DisjointSet(10)
links = [[1,2], [2,3], [3,5], [5, 6]]
for pair in links:
    js.union(pair[0], pair[1])
print(js.tree_num())
print(js)

# 6
# items: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
# index: [0, 2, 5, 2, 4, 5, 5, 7, 8, 9]
# depth: [0, 0, 1, 0, 0, 1, 0, 0, 0, 0]
# CPU times: user 4 ms, sys: 0 ns, total: 4 ms
# Wall time: 143 µs