Find First Element of Loop in Linked List

C++ Code:

void find_loop_beginning(Node *head){

    Node *slow = head;

    Node *fast = head;

    if (!head || !(head->next))

        return;

    while(slow && fast && fast->next){

        slow = slow->next;

        fast = fast->next->next;

        if(slow == fast)

            break;

    }

    

    // No Loop exixts

    if (slow != fast){

        std::cout << "No Loop" << std::endl;

        return;

    }

    

    // When Loop exists

    slow = head;

    while(slow != fast){

        slow = slow->next;

        fast = fast->next;

    }

    std::cout << "First loop element = " << slow->data << std::endl;

}

Detailed explanation can be found on Youtube:

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