| 说到链表的反转，当初第一次接触这个概念的时候，首先想到的办法就是，首先对链表做一个遍历，强行给每个节点记录一个顺序，然后再根据顺序重新构建列表，这种办法虽然可以实现，但是效率不高（主要是取决重新排序生成列表的排序算法复杂度），下面这个办法的算法复杂度仅仅为O（N），附代码
// Java program for reversing the linked list
class LinkedList {
static Node head;
static class Node {
int data;
Node next;
Node(int d) {
data = d;
next = null;
}
}
/* Function to reverse the linked list */
Node reverse(Node node) {
Node prev = null;
Node current = node;
Node next = null;
while (current != null) {
next = current.next;
current.next = prev;
prev = current;
current = next;
}
node = prev;
return node;
}
// prints content of double linked list
void printList(Node node) {
while (node != null) {
System.out.print(node.data + " ");
node = node.next;
}
}
public static void main(String[] args) {
LinkedList list = new LinkedList();
list.head = new Node(85);
list.head.next = new Node(15);
list.head.next.next = new Node(4);
list.head.next.next.next = new Node(20);
System.out.println("Given Linked list");
list.printList(head);
head = list.reverse(head);
System.out.println("");
System.out.println("Reversed linked list ");
list.printList(head);
}
}
|