Given a string, find the length of the longest substring without repeating characters. 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.
1 /**
2 *
3 */
4 package solution;
5
6 import java.util.HashMap;
7
8 /**
9 * @author whh
10 *
11 * Given a string, find the length of the longest substring without
12 * repeating characters. For example, the longest substring without
13 * repeating letters for "abcabcbb" is "abc", which the length is 3. For
14 * "bbbbb" the longest substring is "b", with the length of 1.
15 */
16 public class LongestSubstringWithoutRepeatingCharacters {
17
18 /**
19 * @param args
20 */
21 public static void main(String[] args) {
22 String s1 = "abcabcbb", s2 = "aaa", s3 = "abcdefghijklmnopqrstuvwxyz";
23 String s4 = "wlrbbmqbhcdarzowkk";
24 String s5 = "qopubjguxhxdipfzwswybgfylqvjzhar";
25 System.out.println(lengthOfLongestSubstring(s1));
26 System.out.println(lengthOfLongestSubstring(s2));
27 System.out.println(lengthOfLongestSubstring(s3));
28 System.out.println(lengthOfLongestSubstring(s4));
29 System.out.println(lengthOfLongestSubstring(s5));
30
31 }
32
33 /**
34 * @param s
35 * @return
36 */
37 public static int lengthOfLongestSubstring(String s) {
38
39 HashMap<Character, Integer> map = new HashMap<Character, Integer>();
40
41 int begin = 0, maxLength = 0;
42 for (int end = 0; end < s.length(); end++) {
43 Character character = s.charAt(end);
44 if (!map.containsKey(character)) {
45 map.put(character, 1);
46 } else {
47 map.put(character, map.get(character) + 1);
48 }
49
50 if (map.get(character) == 2) {
51 while (map.get(s.charAt(begin)) <= 1) {
52 map.put(s.charAt(begin), map.get(s.charAt(begin)) - 1);
53 begin++;
54 }
55 map.put(s.charAt(begin), map.get(s.charAt(begin)) - 1);
56 begin++;
57 }
58 if ((end - begin + 1) >= maxLength) {
59 maxLength = end - begin + 1;
60 }
61 }
62
63 return maxLength;
64 }
65 }
