题解 | #链表内指定区间反转#
链表内指定区间反转
https://www.nowcoder.com/practice/b58434e200a648c589ca2063f1faf58c
从原链表中拆出需要反转的子链表，反转完毕之后，重新接入断开的链表
import java.util.*;
/*
* public class ListNode {
* int val;
* ListNode next = null;
* }
*/
public class Solution {
/**
*
* @param head ListNode类
* @param m int整型
* @param n int整型
* @return ListNode类
*/
public ListNode reverseBetween (ListNode head, int m, int n) {
// write code here
ListNode dummy_node = new ListNode(-1);
dummy_node.next = head;
ListNode pre = dummy_node;
for(int i = 1; i < m; i++){
pre = pre.next;
}
ListNode right_node = pre.next;
for(int j = m; j < n; j++){
right_node = right_node.next;
}
ListNode left_node = pre.next;
ListNode succ = right_node.next;
pre.next = null;
right_node.next = null;
reverse(left_node);
pre.next = right_node;
left_node.next = succ;
return dummy_node.next;
}
public void reverse(ListNode head){
ListNode pre = null;
ListNode cur = head;
ListNode succ = null;
while(cur!=null){
succ = cur.next;
cur.next = pre;
pre = cur;
cur = succ;
}
}
}
