ARST打卡第141周[141/521]

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19

class Solution {
    ListNode *head;

public:
    Solution(ListNode *head) {
        this->head = head;
    }

    int getRandom() {
        int i = 1, ans = 0;
        for (auto node = head; node; node = node->next) {
            if (rand() % i == 0) { // 1/i 的概率选中（替换为答案）
                ans = node->val;
            }
            ++i;
        }
        return ans;
    }
};