Length of the Longest Substring without repeating characters

Given a string, find the length of the longest substring without repeating characters. For example, the longest substrings without repeating characters for “ABDEFGABEF” are “BDEFGA” and “DEFGAB”, with length 6. For “BBBB” the longest substring is “B”, with length 1. For “GEEKSFORGEEKS”, there are two longest substrings  with length 7.

https://leetcode.com/articles/longest-substring-without-repeating-characters/

Other Solutions
http://www.programcreek.com/2013/02/leetcode-longest-substring-without-repeating-characters-java/
http://www.ideserve.co.in/learn/longest-substring-with-non-repeating-characters
http://www.geeksforgeeks.org/length-of-the-longest-substring-without-repeating-characters/
http://blog.gainlo.co/index.php/2016/10/07/facebook-interview-longest-substring-without-repeating-characters/

Variation :
http://www.programcreek.com/2014/09/leetcode-longest-substring-with-at-least-k-repeating-characters-java/
http://www.programcreek.com/2013/02/longest-substring-which-contains-2-unique-characters/

http://www.programcreek.com/2014/06/leetcode-substring-with-concatenation-of-all-words-java/