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Q092_ReverseLinkedListII.cs
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Q092_ReverseLinkedListII.cs
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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Microsoft.VisualStudio.TestTools.UnitTesting;
// Reverse a linked list from position m to n. Do it in-place and in one-pass.
// For example:
// Given 1->2->3->4->5->NULL, m = 2 and n = 4,
// return 1->4->3->2->5->NULL.
// Note:
// Given m, n satisfy the following condition:
// 1 <= m <= n <= length of list.
namespace LeetSharp
{
[TestClass]
public class Q092_ReverseLinkedListII
{
public ListNode<int> ReverseBetween(ListNode<int> head, int m, int n)
{
if (m == n)
{
return head;
}
// find pre-changing head
ListNode<int> dummy = new ListNode<int>(0);
dummy.Next = head;
var preChaningHead = dummy;
int changeLength = n - m;
while (m-- > 1)
{
preChaningHead = preChaningHead.Next;
}
var curNode = preChaningHead.Next;
for (int i = 0; i < changeLength; i++)
{
var preNext = preChaningHead.Next;
var curNext = curNode.Next;
curNode.Next = curNext.Next;
preChaningHead.Next = curNext;
curNext.Next = preNext;
}
return dummy.Next;
}
public string SolveQuestion(string input)
{
return ReverseBetween(input.GetToken(0).ToListNode<int>(), input.GetToken(1).ToInt(),
input.GetToken(2).ToInt()).SerializeListNode();
}
[TestMethod]
public void Q092_Small()
{
TestHelper.Run(s => SolveQuestion(s));
}
[TestMethod]
public void Q092_Large()
{
TestHelper.Run(s => SolveQuestion(s));
}
}
}