反转单链表

#include<iostream>

using namespace std;

struct Node{
    int val;
    Node* next;
    Node(int v):val(v),next(NULL){}
};
Node * reverseList(Node* head){
    Node* pre = NULL;
    Node* cur = head;
    Node* cnext = NULL;
    while(cur){
        cnext = cur->next;
        cur->next = pre;
        pre = cur;
        cur = cnext;
    }
    return pre;
}

int main(){
    Node* head = new Node(1);
    head->next = new Node(2);
    head->next->next = new Node(3);
    Node *ans = reverseList(head);
     
    while(ans){
        cout<<ans->val<<" ";
        ans = ans->next;
    }
    return 0;
}