交换链表的奇偶位（比如1和2，3和4，5和6。。。交换）

题目：Given a linked list, swap every two adjacent nodes and return its head.
For example,
Given1->2->3->4, you should return the list as2->1->4->3.
Your algorithm should use only constant space. You may not modify the values in the list, only nodes itself can be changed.

C++代码：
#include 
#include 

using namespace std;

//构造节点
struct Node {
    int element = 0;
    Node* next = NULL;
};

//打印一个链表
void print(Node* header) {
    while(header->next != NULL) {
        cout << header->element << " ";
        header = header->next;
    }
    cout << endl;
}
//创建一个链表
Node* createList(vector m, Node * header) {
    unsigned long count = m.size();
    Node* temp ;
    Node* p = new Node();
    p->next = header;
    for(int i = 0; i < count; i++) {
        header->element = m[i];
        temp = new Node();
        header->next = temp;
        header = temp;
    }
    return p->next;
}
//负责交换的代码
Node* swapList(Node* header) {
    Node* p = new Node();
    p->next = header;
    Node* p1;
    Node* p2;
    Node* temp1;
    Node* temp2 = p;
    while(header->next != NULL) {
        p1 = header;
        p2 = header->next;
        temp1 = p2->next;
        p2->next = p1;
        p1->next = temp1;
        temp2->next = p2;
        temp2 = temp2->next->next;
        header = temp1;
    }
    return p->next;
}

int main() {
    int n;
    cout << "请输入节点的个数（偶数）" << endl;
    cin >> n;
    vector m;
    int x;
    for(int i = 0; i < n; i++) {
        cin >> x;
        m.push_back(x);
    }
    
    Node* header = new Node();
    header = createList(m, header);
    header = swapList(header);
    print(header);
}