逆置单链表

逆置单链表可能是一个非常非常常见的数据结构的题目了
蛮经典的
在这里再写一次。
其实我还是写了蛮久的，汗一个我的编程能力~
只放了main方法 不过够了

public static void main(String[] args) {
		Node a1 = new Node("a",null);
		Node a2 = new Node("b",null);
		Node a3 = new Node("c",null);
		Node a4 = new Node("d",null);
		
		a1.next = a2;
		a2.next = a3;
		a3.next = a4;
		
		
		Node head = a1;
		Node pre = null;
		Node next = head.next;
		
		while(next != null) {
			head.next = pre;
			pre = head;
			head = next;
			next = next.next;
		}
		head.next = pre;
		
		//print all
		Node p;
		p = head;
		for(;p != null;p = p.next) {
			System.out.print(p.value + " ");
		}
	}