This question evaluates understanding of graph connectivity and component aggregation (often involving disjoint-set concepts) along with combinatorial counting to compute cross-group pairs.
You are given n employees labeled from 0 to n - 1 and a list of relationships relations, where each pair [a, b] means employees a and b belong to the same group. Group membership is transitive, so if [0, 1] and [0, 2] are present, then 0, 1, and 2 are all in one group.
Your task is to count how many unordered pairs of employees (i, j) can be formed such that i and j come from different groups.
Example:
n = 5
relations = [[0, 1], [0, 2], [3, 4]]
This creates two groups: {0, 1, 2} and {3, 4}.
The valid cross-group pairs are:
(0, 3)
,
(0, 4)
(1, 3)
,
(1, 4)
(2, 3)
,
(2, 4)
So the answer is 6.
Return the total number of valid pairs.