链表逆序以及python语法糖

用c++写行数特别多，但是用python那就是截然不同，当然了也是因为语法糖的存在
不带头节点的链表写判断还要多几行
下面的方法都会破坏原有链表结构
链表逆序leetcode

ListNode* reverseList(ListNode* head) {
    ListNode *r = NULL;
    ListNode *p = head;
    while (p!=NULL)
    {
        ListNode *s = p->next;
        p->next = r;
        r = p;
        p = s;
     }
     return r;
}

def reverseList(self, head):
    cur, prev = head, None
    while cur:
        cur.next, prev, cur = prev, cur, cur.next
    return prev

链表节点两两互换leetcode

ListNode* swapPairs(ListNode* head) {
    ListNode *r = (ListNode *)malloc(sizeof(ListNode));
    ListNode *l;
    ListNode *p = head;
    r->next = p;
    l=r;
    while (p != NULL && p->next != NULL) {
        ListNode *q = p->next;
        p->next = q->next;
        q->next = p;
        r->next = q;
        r = p;
        p = p->next;
    }
    return l->next;
}

def swapPairs(self, head):
    pre, pre.next = self, head
    while pre.next and pre.next.next:
        a = pre.next
        b = a.next
        pre.next, b.next, a.next = b, a, b.next
        pre = a
    return self.next