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/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
/** @param head The linked list's head.
Note that the head is guaranteed to be not null, so it contains at least one node. */
ListNode *head;
Solution(ListNode* _head): head(_head) {}
/** Returns a random node's value. */
int getRandom() {
int selected = head->val, count = 2;
ListNode *p = head->next;
while (p != nullptr) {
if ((int)((double)rand() / (RAND_MAX + 1u) * count) == 0) {
selected = p->val;
}
p = p->next;
count++;
}
return selected;
}
};
/**
* Your Solution object will be instantiated and called as such:
* Solution obj = new Solution(head);
* int param_1 = obj.getRandom();
*/