The Earliest Moment When Everyone Become Friends

Problem: The Earliest Moment When Everyone Become Friends There are n people labeled from 0 to n - 1. You are given an array logs, where each log is: [timestamp, a, b] It means that person a and person b become friends at time timestamp. Friendship is transitive: if a is connected to b, and b is connected to c, then a and c are in the same friend group. Return the earliest timestamp when all n people become connected. If it never happens, return -1. Input Format The first line contains two integers n and m, where n is the number of people and m is the number of logs. The next m lines each contain three integers: timestamp a b Output Format Print one integer: the earliest timestamp when everyone is connected, or -1 if impossible. Constraints 2 <= n <= 10^5 0 <= m <= 2 * 10^5 0 <= timestamp <= 10^9 0 <= a, b < n a != b Follow-up If there are blocked nodes or blocked edges that prevent traversal or direct connection, first clarify what “blocked” means, then use BFS/DFS to check reachability after excluding the blocked elements. Example Input 6 8 20190101 0 1 20190104 3 4 20190107 2 3 20190211 1 5 20190224 2 4 20190301 0 3 20190312 1 2 20190322 4 5 Output 20190301