Longest Substring without repeating characters

Longest Substring without repeating characters

Given a string, find the length of the longest substring without repeating characters. For example, the longest substring without repeating letters for "ABCABCBB" are "abc", which the length is 3. For "bbbbb" the longest substring are "B", with the length of 1.

began to use the exhaustive method, all the substrings are traversed out, the result is timed out.

1  Public classSolution {2      Public intlengthoflongestsubstring (String s) {3         if(s.length () = = 0){4             return0;5         }6         if(s.length () = = 1)7             return1;8         intresult = 1;9          for(inti = 0; I < s.length ()-result; i++){Ten             intj = i + 1; One              for(; J < S.length (); j + +){ AString Sub =s.substring (i, j); -                 if(-1 = =Sub.indexof (S.charat (j))) -                 { the                     if(Sub.length () + 1 >result) -result = Sub.length () + 1; -                     Continue; -                 } +                  Break; -             } +         } A          at         returnresult; -     } -}

Referring to others, only traversing the string once, using the hash table to record the location of S.charat (i). Constantly updated result, a bit greedy algorithm feel, each time the current string to record the starting position

Reference connection I'm too lazy to find it.

Importjava.util.Hashtable; Public classSolution { Public intlengthoflongestsubstring (String s) {if(s.length () = = 0){            return0; }        if(s.length () = = 1)            return1; intresult = 0;//The result of the last return        intindex =-1;//the previous position of the current substring start positionHashtable<character, integer> map =NewHashtable<character, integer> ();//S[i] where it appears                 for(inti = 0; I < s.length (); i++) {Integer position=Map.get (S.charat (i)); if(NULL! = Position && position >index) Index=position; if(I-index >result) Result= i-index;        Map.put (S.charat (i), i); }                returnresult; }}

Longest Substring without repeating characters