49 lines
1.1 KiB
Java
49 lines
1.1 KiB
Java
/*
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* @lc app=leetcode id=92 lang=java
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*
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* [92] Reverse Linked List II
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*/
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// @lc code=start
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/**
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* Definition for singly-linked list.
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* public class ListNode {
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* int val;
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* ListNode next;
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* ListNode() {}
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* ListNode(int val) { this.val = val; }
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* ListNode(int val, ListNode next) { this.val = val; this.next = next; }
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* }
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*/
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class Solution {
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/**
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* 链表逆序：头插法
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* @param head
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* @param left
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* @param right
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* @return
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*/
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public ListNode reverseBetween(ListNode head, int left, int right) {
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ListNode dummy = new ListNode(0);
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dummy.next = head;
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ListNode prev, frm;
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prev = frm = dummy;
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for(int i = 0; i<left-1; i++) {
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prev = prev.next;
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}
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for(int i = 0; i < left; i++) {
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frm = frm.next;
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}
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ListNode cur;
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for(int i = 0; i<right-left; i++) {
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cur = frm.next;
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frm.next = cur.next;
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cur.next = prev.next;
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prev.next = cur;
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}
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return dummy.next;
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}
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}
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// @lc code=end
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