LeetCode 382. 链表随机节点

我的解题

#include <bits/stdc++.h>
using namespace std;

/**
 * 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) {}
 * };
 */
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
{
    ListNode *m_head;
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. */
    Solution(ListNode *head) :
                    m_head { head }
    {
        srand((unsigned) time(NULL));
    }

    /** Returns a random node's value. */
    int getRandom()
    {

        int res = m_head->val;
        ListNode *node = m_head->next;
        int k = 2;
        while (node)
        {
            if (rand() % k == 0)
            {
                res = node->val;
            }
            node = node->next;
            ++k;
        }
        return res;
    }
};

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

int main()
{

}
// g++ test.cpp --std=c++11 -pedantic -Wall -Wextra