Class Solution
-
- All Implemented Interfaces:
public final class Solution
382 - Linked List Random Node.
Medium
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:
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 <code>1, 10<sup>4</sup></code>.
<code>-10<sup>4</sup><= Node.val <= 10<sup>4</sup></code>
At most <code>10<sup>4</sup></code> 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?