链表的反转

package Struct;

public class ListNode {
    public int val;
    public ListNode next = null;

    public ListNode(int val) {
        this.val = val;
    }
}

package offer;

import Struct.ListNode;

/**
 * 
 * 
 * 链表反转输出链表的头
 *  
 *
 *
 * @author 爱不会绝迹
 *
 */
public class Problem05 {
        /**
          * 链表的反转可以利用头插法将链表的节点顺序倒置
          */
    public static ListNode ReverseList(ListNode head) {
        ListNode h = new ListNode(-1);
        ListNode p = head;
        ListNode p1 = p;
        while(p1 != null){
            p1 = p1.next;
            p.next = h.next;                
            h.next = p;    
            p = p1;
        }
        return h.next;
    }
    public static void main(String[] args) {
        ListNode head = new ListNode(1);
        ListNode p = null;
        for(int i = 5;i >1;i --){
            p = new ListNode(i);
            p.next = head.next;
            head.next = p;
        }
        ReverseList(head);
    }
}

 链表的反转