在链表中添加头节点

#include <iostream>

using namespace std;

struct Node{
    int val;
    Node* next;
    
    Node(int _val) : val(_val), next(NULL) {}
};

int main(){
    Node* p = new Node(1);
    Node* q = new Node(2);
    Node* o = new Node(3);
    
    p->next = q;
    q->next = o;
    
    Node* head = p;
    //添加节点
    Node* u = new Node(4);
    u->next = head;
    head = u;
    
    for(Node* i = head; i; i = i->next){
        cout << i->val << endl;
    }
    
    return 0;
}