## 382. Linked List Random Node

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.

Example 1:

```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`.

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

## Rust Solution

``````use rand::prelude::*;
use rustgym_util::*;

struct Solution {
}

impl Solution {
}

fn get_random(&mut self) -> i32 {
let mut res = 0;
let mut count = 0;
while let Some(node) = cur {
let val = node.val;
count += 1;
if self.rng.gen_range(0, count) == 0 {
res = val;
}
cur = &node.next;
}
res
}
}
``````

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