Given a string, find the length of the longest substring without repeating characters.
Example
For example, the longest substring without repeating letters for"abcabcbb" is "abc", which the length is 3.
For "bbbbb" the longest substring is "b", with the length of 1.
Challenge
O(n) time
LeetCode上的原题，请参见我之前的博客Longest Substring Without Repeating Characters。
解法一：
class Solution { public: /** * @param s: a string * @return: an integer */ int lengthOfLongestSubstring(string s) { int res = 0, left = -1; vector<int> m(256, -1); for (int i = 0; i < s.size(); ++i) { left = max(left, m[s[i]]); m[s[i]] = i; res = max(res, i - left); } return res; } };
解法二：
class Solution { public: /** * @param s: a string * @return: an integer */ int lengthOfLongestSubstring(string s) { int res = 0, left = 0, right = 0; unordered_set<char> st; while (right < s.size()) { if (!st.count(s[right])) { st.insert(s[right++]); res = max(res, (int)st.size()); } else { st.erase(s[left++]); } } return res; } };
本文转自博客园Grandyang的博客，原文链接：[LintCode] Longest Substring Without Repeating Characters，如需转载请自行联系原博主。