Does my solution return with equal probability[C++]?

  • 2

    I generate the a number for each node and return the node with the highest generated value.
    Each node has a 1/n probability of generating the largest value and thus has a 1/n probability of being returned.

    int getRandom() {
            int maxNumber = 0;
            int maxNodeValue = 0;
            ListNode * current = head;
            std::random_device rd;
            std::mt19937 gen(rd());
            std::uniform_int_distribution<> dis(1, 1000000000);
            while(current != NULL) {
                int rand = dis(gen);
                if(rand > maxNumber) {
                    maxNumber = rand;
                    maxNodeValue = current->val;
                current = current->next;
            return maxNodeValue;

  • 0

    Very creative and neat. It's not quite perfect, because earlier nodes have the advantage in case of ties, but that's rare.

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