2、无重复字符的最长子串

public static int CalcNoRepeatCount(string characterStr)
{
int length = characterStr.Length;
int currentCount = 0;
int maxCount = 0;
int left = 0;
List<string> cacheList = new List<string>();
List<string> maxList = new List<string>();
for (int i = 0; i < length; i++)
{
currentCount += 1;
while (cacheList.Contains(characterStr.Substring(i, 1)))
{

cacheList.Remove(characterStr.Substring(left, 1));
left += 1;
currentCount -= 1;

}
cacheList.Add(characterStr.Substring(i, 1));
if (currentCount > maxCount)
{
maxCount = currentCount;
maxList.Clear();
foreach (var item in cacheList)
{
maxList.Add(item);
}
}

}
string substr = "";
foreach (var item in maxList)
{
substr += item;
}
Console.WriteLine(substr);
return maxCount;
}