# 力扣第三題 C#版

請注意，你的答案必須是 子串 的長度，"pwke" 是一個子序列，不是子串。

## 1、笨辦法

``````using System.Collections.Generic;

namespace Algorithm
{
public class Solution
{
public int LengthOfLongestSubstring(string s)
{
int maxLength = 0;
char[] cs = s.ToCharArray();
int temp;
HashSet<char> ciDic = new HashSet<char>();
for (int i = 0; i < cs.Length; i++)
{
ciDic = new HashSet<char>();
for (int j = i; j < cs.Length; j++)
{
{
temp = j - i;
if (temp > maxLength) maxLength = temp;
break;
}

else if (j == cs.Length - 1)
{
temp = j - i+1;
if (temp > maxLength) maxLength = temp;
break;
}
}
}
return maxLength;
}
}
}
``````

## 2、稍好辦法

``````using System;
using System.Collections.Generic;

namespace Algorithm
{
public class Solution
{
public int LengthOfLongestSubstring(string s)
{
int i = 0;
int j = 0;
int maxLength=0;
char[] cs = s.ToCharArray();
int n = s.Length;
HashSet<char> cSet = new HashSet<char>();
while (i < n && j < n)
{
if (!cSet.Contains(cs[j]))
{
j++;
maxLength = Math.Max(maxLength, j - i);
}
else
{
cSet.Remove(cs[i]);
i++;
}
}
return maxLength;
}
}
}
``````