将单链表的顺序翻转过来
代码实现# 定义链表节点
static class ListNode{
int val;
ListNode next;
public ListNode(int val,ListNode next){
this.val = val;
this.next = next;
}
}
1. 迭代方法
// 迭代
public static ListNode iterate(ListNode head){
ListNode prev=null,next;
ListNode curr = head;
while(curr != null){
next = curr.next;
curr.next = prev;
prev = curr;
curr = next;
}
return prev;
}
2. 递归方法
public static ListNode recursion(ListNode head){
if(head == null || head.next == null){
return head;
}
ListNode new_head = recursion(head.next);
head.next.next = head;
head.next = null;
return new_head;
}
3. main（）函数
public static void main(String[] args) {
ListNode node5 = new ListNode(5,null);
ListNode node4 = new ListNode(4,node5);
ListNode node3 = new ListNode(3,node4);
ListNode node2 = new ListNode(2,node3);
ListNode node1 = new ListNode(1,node2);
ListNode prev1 = iterate(node1);
ListNode prev2 = recursion(node1);
System.out.println(prev1);
}
