Leetcode Linked List Random Node problem solution

class Solution:

    def __init__(self, head: ListNode):
        """
        @param head The linked list's head.
        Note that the head is guaranteed to be not null, so it contains at least one node.
        """
        self.values=[]
        while head:
            self.values.append(head.val)
            head=head.next

    def getRandom(self) -> int:
        """
        Returns a random node's value.
        """
        import random
        return self.values[random.randint(0,len(self.values)-1)]

class Solution {

List<Integer> arr = null;
Random rand;

public Solution(ListNode head) {
    ListNode ptr = head;
    this.arr = new ArrayList<>();
    while(ptr != null){
        arr.add(ptr.val);
        ptr = ptr.next;
    }
    this.rand = new Random();
}

/** Returns a random node's value. */
public int getRandom() {
    return this.arr.get(this.rand.nextInt(this.arr.size()));
}
}

class Solution {
public:
    vector<int>vec;
    Solution(ListNode* head) {
        while(head){
            vec.push_back(head->val);
            head = head->next;
        }
    }
    int getRandom() {
        return vec[rand()%vec.size()];
    }
};

typedef struct {
    struct ListNode* head
} Solution;

Solution* solutionCreate(struct ListNode* head) {
    srand(time(NULL));
    Solution* sul = malloc(sizeof(Solution));
    sul->head=head;
    return sul;
}

int solutionGetRandom(Solution* obj) {
    
    int count = 0;
    struct ListNode* temp;
    struct ListNode* head;
    temp = obj->head;
    head = temp;
    int i;
    while(head!=NULL)
    {
        head=head->next;
        count++;
    }

    int  r= random()%count; 
    head = temp;
    for(i=0;i<r;i++)
    {
        head = head->next;
    }

    return head->val;
}

void solutionFree(Solution* obj) {
    free(obj);
}