[数据结构与算法]牛客 --链表反转

package nk;
class ListNode {
    int val;
    ListNode next = null;

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

	@Override
	public String toString() {
		return "ListNode [val=" + val + ", next=" + next + "]";
	}
}

public class Solution {
	
	public static void main(String[] args) {
		ListNode head = new ListNode(1);
		ListNode tmp = head;
		for(int i = 2; i < 6; i++){
			ListNode n = new ListNode(i);
			tmp.next = n;
			tmp = n;
		}
		
		print(head);
		
		print(ReverseList(head));
	}
	
    public static ListNode ReverseList(ListNode head) {
    	ListNode newHead = new ListNode(0);
    	if(head == null) return head;
    	while(head != null){
    		ListNode tmp = newHead.next;
    		ListNode n = new ListNode(head.val);
    		n.next = tmp;
    		newHead.next = n;
    		head = head.next;
    	}
    	return newHead.next;
    }
    
    public static void print(ListNode head){
    	while(head != null){
    		System.out.print(head.val + "	");
    		head = head.next;
    	}
    	System.out.println("");
    }
}