struct ListNode *getIntersectionNode(struct ListNode *headA, struct ListNode *headB) {
    struct ListNode* pA = headA;
    struct ListNode* pB = headB;
    if(pA == NULL || pB == NULL)
    {
        return NULL;
    }
    while(pA != pB)
    {
        pA = pA == NULL ? headB : pA->next;
        pB = pB == NULL ? headA : pB->next;
    }
    return pA;
}