2020-09-11

反转链表

public class ListNode{
	int val;
	ListNode next = null;
	ListNode(int val){
		this.val = val;
	}
}
public class Solution {
    public ListNode ReverseList(ListNode head) {
        ListNode res = new ListNode(0);   //定义一个头结点，用于指向要返回的链表
        ListNode curr = head;	//当前要处理的结点
        while(curr != null){	//当结点不为空时处理
            ListNode next = curr.next;	//保存当前结点后面的结点信息
            curr.next = res.next;	//当前结点指向头结点后面的信息
            res.next = curr;	//头结点指向当前结点
            curr = next;		//当前结点后移
        }
        return res.next;		//返回链表
    }
}