[LeetCode] 3. Longest Substring Without Repeating Characters（自学留存）

Given a string, find the length of the longest substring without repeating characters.

Examples:

Given "abcabcbb", the answer is "abc", which the length is 3.

Given "bbbbb", the answer is "b", with the length of 1.

Given "pwwkew", the answer is "wke", with the length of 3. Note that the answer must be a substring, "pwke" is a subsequence and not a substring.

Personal Tips:  使用map。但是看LeetCode上面参考可以使用另一个数组。代码如下：

class Solution {
public:
	int lengthOfLongestSubstring(string s) {
		if (s.empty()) return 0;
		int pos = 0, left = 0, right = 0, length = 0, max = 1;map<char, int> num;
		while (right <= s.size())
		{	
			if (num.count(s[right]))
			{
				if (num[s[right]] >= left)
				{
					length = right - left;
					if (max < length)
					{
						max = length;
						pos = left;
					}
					left = (num[s[right]] + 1); 
					num[s[right]] = right;
					++right;
					continue;
				}
				else
				{
					num[s[right]] = right;
					++right;
					continue;
				}
			}
			else if (right >= (s.size() - 1))
			{
				length = s.size() - left;
				if (max < length)
				{
					max = length;
					pos = left;
				}
				break;
			}
			num.insert(pair<char, int>(s[right], right));
			++right;
		}
		return max;
	}
};