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LinkedListRandomNode.java
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LinkedListRandomNode.java
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package linkedlist;
import utils.LeetCode;
import utils.Level;
import java.util.Random;
@LeetCode(no=382, title = "Linked List Random Node", url = "https://leetcode.com/problems/linked-list-random-node/",level = Level.MEDIUM
)
public class LinkedListRandomNode {
}
/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode() {}
* ListNode(int val) { this.val = val; }
* ListNode(int val, ListNode next) { this.val = val; this.next = next; }
* }
*/
class Solution {
int size=0;
ListNode head;
/** @param head The linked list's head.
Note that the head is guaranteed to be not null, so it contains at least one node. */
public Solution(ListNode head) {
ListNode node= head;
this.head=head;
while(node!=null){
size++;
node=node.next;
}
}
/** Returns a random node's value. */
public int getRandom() {
Random r = new Random();
int low = 0;
int high = size;
int result = r.nextInt(high-low) + low;
ListNode node= this.head;
while(low!=result){
low++;
node= node.next;
}
return node.val;
}
}
/**
* Your Solution object will be instantiated and called as such:
* Solution obj = new Solution(head);
* int param_1 = obj.getRandom();
*/