反转链表
题目:![](data:image/png;base64,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)
思路:
-
遍历法
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判断当前的头结点是否为空,若不为空进入循环
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将头结点的下一节点取出赋值给next节点
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然后将头结点的下一节点指向pre(然后将当前头结点的指赋值给pre,因为java没有指针,这种赋值的方式不会改变内部的指针指向,即head的操作实际第一步为1->null,第二次为2->1->null,第三次为3->2->1->null,实际只是将地址引用的值赋值给了pre)
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将next赋值给head,即将余剩的链接变为新的链接传下去
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递归法
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我们来看是怎样的一个递归过程:1->2->3->4
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程序到达Node newHead = reverse(head.next);时进入递归
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我们假设此时递归到了3结点,此时head=3结点,temp=3结点.next(实际上是4结点)
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执行Node newHead = reverse(head.next);传入的head.next是4结点,返回的newHead是4结点。
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接下来就是弹栈过程了
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程序继续执行 temp.next = head就相当于4->3
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head.next = null 即把3结点指向4结点的指针断掉。
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返回新链表的头结点newHead
代码示例:
int val;
ListNode next = null;
}
public class Solution {
public static void main(String[] args) {
ListNode node = new ListNode(), top = node;
node.val = 1;
for (int i = 2; i < 10; i++) {
ListNode newNode = new ListNode();
newNode.val = i;
node.next = newNode;
node = newNode;
}
//这里是用于打印出你原本所设置的链表的全部,之所以要赋值,是因为链表是一个个的遍历下去的当指向最后一个时不容易找到头指针
ListNode temp = top;
while (temp.next != null) {
System.out.println(temp.val);
temp = temp.next;
}
System.out.println(temp.val);
System.out.println("");
// //这里用遍历法进行反转
// ListNode data = reverseIteratively1(top);
// //将反转后的进行打印
// while (data.next != null) {
// System.out.println(data.val);
// data = data.next;
// }
// System.out.println(data.val);
//这里用递归法进行反转
ListNode data = reverseIteratively2(top);
//将反转后的进行打印
while (data.next != null) {
System.out.println(data.val);
data = data.next;
}
System.out.println(data.val);
}
/**
* 递归法
*
* @param head
* @return
*/
public static ListNode reverseIteratively2(ListNode head) {
if (head == null || head.next == null)
return head;
ListNode temp = head.next;
ListNode newHead = reverseIteratively2(head.next);
temp.next = head;
head.next = null;
return newHead;
}
/**
* 遍历法
*
* @param head
* @return
*/
public static ListNode reverseIteratively1(ListNode head) {
ListNode pre = null;
ListNode next = null;
while (head != null) {
next = head.next;
head.next = pre;
pre = head;
head = next;
}
return pre;
}
}