使用头插法建立双向链表
public static DoubleNode init(List<DoubleNode> doubleNodes) {
DoubleNode head = new DoubleNode(0);
DoubleNode dummy = head;
head.next = null;
head.pre = null;
for (int i = 0; i < doubleNodes.size(); i++) {
doubleNodes.get(i).next = head.next; // 头插法建立双向链表 带头节点的双向链表
head.next = doubleNodes.get(i);
doubleNodes.get(i).pre = head;
}
return dummy;
}