题解 | #两两交换链表的节点#

 * function ListNode(x){
 *   this.val = x;
 *   this.next = null;
 * }
 */
/**
 * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 *
 * 
 * @param head ListNode类 
 * @return ListNode类
 */
function swapLinkedPair( head ) {
    if(!head || !head.next)    return head
    let cur = head,left = head,right = head,pre = head
    head = head.next
    while(cur && cur.next){
        let tmp = cur.next.next
        right = cur.next
        pre.next = right
        left = cur
        left.next = tmp
        right.next = left
        cur = tmp
        pre = left
    }
    return head
}
module.exports = {
    swapLinkedPair : swapLinkedPair
};