public class Solution
extends Object
1319 - Number of Operations to Make Network Connected\.
Medium
There are `n` computers numbered from `0` to `n - 1` connected by ethernet cables `connections` forming a network where connections[i] = [ai, bi] represents a connection between computers ai and bi. Any computer can reach any other computer directly or indirectly through the network.
You are given an initial computer network `connections`. You can extract certain cables between two directly connected computers, and place them between any pair of disconnected computers to make them directly connected.
Return _the minimum number of times you need to do this in order to make all the computers connected_. If it is not possible, return `-1`.
**Example 1:**
**Input:** n = 4, connections = \[\[0,1],[0,2],[1,2]]
**Output:** 1
**Explanation:** Remove cable between computer 1 and 2 and place between computers 1 and 3.
**Example 2:**
**Input:** n = 6, connections = \[\[0,1],[0,2],[0,3],[1,2],[1,3]]
**Output:** 2
**Example 3:**
**Input:** n = 6, connections = \[\[0,1],[0,2],[0,3],[1,2]]
**Output:** -1
**Explanation:** There are not enough cables.
**Constraints:**
* 1 <= n <= 105
* 1 <= connections.length <= min(n * (n - 1) / 2, 105)
* `connections[i].length == 2`
* 0 <= ai, bi < n
* ai != bi
* There are no repeated connections.
* No two computers are connected by more than one cable.