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# 1319. Number of Operations to Make Network Connected

<https://leetcode.com/problems/number-of-operations-to-make-network-connected>

## Description

There are `n` computers numbered from `0` to `n-1` connected by ethernet cables `connections` forming a network where `connections[i] = [a, b]` represents a connection between computers `a` and `b`. Any computer can reach any other computer directly or indirectly through the network.

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's not possible, return -1.&#x20;

**Example 1:**

![](https://assets.leetcode.com/uploads/2020/01/02/sample_1_1677.png)

```
**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:**

![](https://assets.leetcode.com/uploads/2020/01/02/sample_2_1677.png)

```
**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.
```

**Example 4:**

```
**Input:** n = 5, connections = [[0,1],[0,2],[3,4],[2,3]]
**Output:** 0
```

**Constraints:**

* `1 <= n <= 10^5`
* `1 <= connections.length <= min(n*(n-1)/2, 10^5)`
* `connections[i].length == 2`
* `0 <= connections[i][0], connections[i][1] < n`
* `connections[i][0] != connections[i][1]`
* There are no repeated connections.
* No two computers are connected by more than one cable.

## ac

```java
```