最长不重复字符的子字符串

题目：请从字符串中找出一个最长的不包含重复字符的子字符串，计算该最长子字符串的长度。假设字符串中只包含从'a'到'z'的字符。

动态规划

//动态规划
int longestSubstingWithoutDuplication(const std::string &str)
{
	int curLength = 0;
	int maxLength = 0;
	int* position = new int[26];
	for (int i = 0;i < 26;++i)
		position[i] = -1;
	for (int i = 0;i < str.size();++i)
	{
		int prevIndex = position[str[i] - 'a'];
		if (prevIndex<0 || i - prevIndex>curLength)
			++curLength;
		else
		{
			if (curLength > maxLength)
				maxLength = curLength;
			curLength = i - prevIndex;
		}
		position[str[i] - 'a'] = i;
	}
	if (curLength > maxLength)
		maxLength = curLength;
	delete[] position;
	return maxLength;
}