public ListNode reverseList(ListNode head) {
ListNode pre = null, cur = head;
while (cur != null) {
ListNode temp = cur.next;
cur.next = pre;
pre = cur;
cur = temp;
}
return pre;
}
7、反转链表Ⅱ:反转left到right的元素【头插法来解决】
public ListNode reverseBetween(ListNode head, int left, int right) {
// 防止left为1,使用虚拟头结点来解决
ListNode virtualNode = new ListNode();
virtualNode.next = head;
ListNode pre = virtualNode, cur;
for (int i = 0; i < left - 1; i++) {
pre = pre.next;
}
cur = pre.next;
for (int i = left; i < right; i++) {
ListNode next = cur.next;
cur.next = next.next;
next.next = pre.next;
pre.next = next;
}
return virtualNode.next;
}