Description

Submission

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
class Solution {
    int count;
    ListNode* head;
public:
    Solution(ListNode* head) {
        count = 0;

        for(ListNode* ptr = head; ptr != nullptr; ptr = ptr->next) ++count;

        this->head = head;
    }
    
    int getRandom() {
        int n = rand() % count;
        ListNode* ptr = head;
        for(int i = 0; i < n; ++i) ptr = ptr->next;

        return ptr->val;
    }
};

/**
 * Your Solution object will be instantiated and called as such:
 * Solution* obj = new Solution(head);
 * int param_1 = obj->getRandom();
 */