按之前题目要求补全以下代码/*-------------------------------------------------- 编程要求 函数node* insertBefore(node* head, node* tmp)的功能是将节点tmp插入到其对“偶节”点前面，并返回新链表。 如果不存在对偶节点，则将tmp插入链表头部。所谓的“对偶”节点是指他们的data值的和为0。 说明：链表head中节点的data值各不相同。 ------------------------------------------------*/ #include <iostream> using namespace std; struct node { int data; node* next; }; node* insertBefore(node* head, node* tmp); void output(node* head); int main() { int n; cin >> n; node* head = NULL, * tmp; bool flag; for (int i = 0; i < n; i++) { tmp = new node; cin >> tmp->data; tmp->next = head; head = tmp; } //output(head); // insert a node after its dual number tmp = new node; cin >> tmp->data; head = insertBefore(head, tmp); output(head); } void output(node* head) { while (head) { cout << head->data; head = head->next; if (head) cout << "->"; } cout << endl; }

好的，以下是完整的代码实现：

#include <iostream>
using namespace std;

struct node {
    int data;
    node* next;
};

node* insertBefore(node* head, node* tmp);
void output(node* head);

int main() {
    int n;
    cin >> n;
    node* head = NULL, * tmp;
    bool flag;
    for (int i = 0; i < n; i++) {
        tmp = new node;
        cin >> tmp->data;
        tmp->next = head;
        head = tmp;
    }
    //output(head);

    // insert a node after its dual number
    tmp = new node;
    cin >> tmp->data;
    head = insertBefore(head, tmp);
    output(head);
}

void output(node* head) {
    while (head) {
        cout << head->data;
        head = head->next;
        if (head) cout << "->";
    }
    cout << endl;
}

node* insertBefore(node* head, node* tmp) {
    if (head == nullptr) {
        return tmp;
    }

    node* pre = head;
    node* cur = head->next;
    int sum = tmp->data + head->data;

    while (cur != nullptr && sum != 0) {
        sum += cur->data;
        pre = cur;
        cur = cur->next;
    }

    if (sum == 0) {
        tmp->next = cur;
        pre->next = tmp;
    } else {
        tmp->next = head;
        head = tmp;
    }

    return head;
}