The Earliest Moment When Everyone Become Friends
Medium · Graphs · about 20 minutes
Asked at Google, Uber, Amazon, Meta.
There are n people 0..n-1. logs[i] = [timestamp, x, y] means x and y become friends at timestamp. Friendship is transitive for acquaintance: if a knows b and b knows c, then a is acquainted with c. Return the earliest time at which everyone is acquainted with everyone else, or -1 if it never happens.