对单链表A、B，编写算法求A=A∩B，A=A∪B的完整代码

以下是求A=A∩B，A=A∪B的完整代码（C++实现）：

#include <iostream>
#include <unordered_set>

using namespace std;

struct ListNode {
    int val;
    ListNode* next;
    ListNode(int x) : val(x), next(NULL) {}
};

ListNode* getIntersectionNode(ListNode* headA, ListNode* headB) {
    unordered_set<ListNode*> set;
    ListNode* cur = headA;
    while (cur != NULL) {
        set.insert(cur);
        cur = cur->next;
    }
    cur = headB;
    while (cur != NULL) {
        if (set.count(cur) > 0) {
            return cur;
        }
        cur = cur->next;
    }
    return NULL;
}

void mergeList(ListNode* headA, ListNode* headB) {
    ListNode* curA = headA, * curB = headB;
    while (curA != NULL && curB != NULL) {
        if (curA->val < curB->val) {
            curA = curA->next;
        }
        else if (curA->val > curB->val) {
            ListNode* tmp = curB->next;
            curB->next = curA;
            headA = curB;
            curB = tmp;
        }
        else {
            curA = curA->next;
            curB = curB->next;
        }
    }
    if (curB != NULL) {
        ListNode* tailA = headA;
        while (tailA->next != NULL) {
            tailA = tailA->next;
        }
        tailA->next = curB;
    }
}

int main() {
    // 构造链表 A
    ListNode* headA = new ListNode(1);
    headA->next = new ListNode(2);
    headA->next->next = new ListNode(3);
    headA->next->next->next = new ListNode(4);

    // 构造链表 B
    ListNode* headB = new ListNode(2);
    headB->next = new ListNode(4);
    headB->next->next = new ListNode(6);

    // 求 A=A∩B
    ListNode* intersection = getIntersectionNode(headA, headB);
    if (intersection != NULL) {
        ListNode* cur = headA;
        while (cur != intersection) {
            cur = cur->next;
            headA = headA->next;
        }
        while (cur != NULL) {
            cur = cur->next;
            headA = headA->next;
        }
        headA = NULL;
    }

    // 求 A=A∪B
    mergeList(headA, headB);

    // 输出链表 A
    ListNode* cur = headA;
    while (cur != NULL) {
        cout << cur->val << " ";
        cur = cur->next;
    }
    cout << endl;

    return 0;
}

其中，`getIntersectionNode`函数用于求A=A∩B，`mergeList`函数用于求A=A∪B。在主函数中，我们构造了链表A和链表B，并分别调用了这两个函数来求解两个问题。最后输出链表A的所有节点值。