已知两个非降序链表序列S1与S2，设计函数构造出S1与S2的交集新链表S3。c++代码

#include <stdio.h>
#include <stdlib.h>

typedef struct ListNode {
    int val;
    struct ListNode *next;
} ListNode;

ListNode* createList(int arr[], int n) {
    if (n == 0) {
        return NULL;
    }
    ListNode *head = (ListNode*)malloc(sizeof(ListNode));
    head->val = arr[0];
    head->next = NULL;
    ListNode *p = head;
    for (int i = 1; i < n; i++) {
        p->next = (ListNode*)malloc(sizeof(ListNode));
        p->next->val = arr[i];
        p->next->next = NULL;
        p = p->next;
    }
    return head;
}

void printList(ListNode *head) {
    if (head == NULL) {
        printf("NULL\n");
        return;
    }
    while (head != NULL) {
        printf("%d->", head->val);
        head = head->next;
    }
    printf("NULL\n");
}

ListNode* getIntersectionNode(ListNode* headA, ListNode* headB) {
    if (headA == NULL || headB == NULL) {
        return NULL;
    }
    ListNode *p1 = headA;
    ListNode *p2 = headB;
    while (p1 != p2) {
        p1 = (p1 == NULL ? headB : p1->next);
        p2 = (p2 == NULL ? headA : p2->next);
    }
    return p1;
}

int main() {
    int arr1[] = {1, 2, 3, 4, 7};
    int arr2[] = {2, 4, 6, 7, 8};
    ListNode *head1 = createList(arr1, 5);
    ListNode *head2 = createList(arr2, 5);
    printf("List 1: ");
    printList(head1);
    printf("List 2: ");
    printList(head2);
    printf("Intersection: ");
    printList(getIntersectionNode(head1, head2));
    return 0;
}