# 0382. Linked List Random Node

<https://leetcode.com/problems/linked-list-random-node>

## Description

Given a singly linked list, return a random node's value from the linked list. Each node must have the **same probability** of being chosen.

Implement the `Solution` class:

* `Solution(ListNode head)` Initializes the object with the integer array nums.
* `int getRandom()` Chooses a node randomly from the list and returns its value. All the nodes of the list should be equally likely to be choosen.

**Example 1:**

![](https://assets.leetcode.com/uploads/2021/03/16/getrand-linked-list.jpg)

```
**Input**
["Solution", "getRandom", "getRandom", "getRandom", "getRandom", "getRandom"]
[[[1, 2, 3]], [], [], [], [], []]
**Output**
[null, 1, 3, 2, 2, 3]
**Explanation**
Solution solution = new Solution([1, 2, 3]);
solution.getRandom(); // return 1
solution.getRandom(); // return 3
solution.getRandom(); // return 2
solution.getRandom(); // return 2
solution.getRandom(); // return 3
// getRandom() should return either 1, 2, or 3 randomly. Each element should have equal probability of returning.
```

**Constraints:**

* The number of nodes in the linked list will be in the range `[1, 104]`.
* `-104 <= Node.val <= 104`
* At most `104` calls will be made to `getRandom`.

**Follow up:**

* What if the linked list is extremely large and its length is unknown to you?
* Could you solve this efficiently without using extra space?

## ac

```java
```