LeetCode: Longest Substring Without Repeating Characters

/**
 * 
 */
package solution;

import java.util.HashMap;

/**
 * @author whh
 * 
 *         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.
 */
public class LongestSubstringWithoutRepeatingCharacters {

    /**
     * @param args
     */
    public static void main(String[] args) {
        String s1 = "abcabcbb", s2 = "aaa", s3 = "abcdefghijklmnopqrstuvwxyz";
        String s4 = "wlrbbmqbhcdarzowkk";
        String s5 = "qopubjguxhxdipfzwswybgfylqvjzhar";
        System.out.println(lengthOfLongestSubstring(s1));
        System.out.println(lengthOfLongestSubstring(s2));
        System.out.println(lengthOfLongestSubstring(s3));
        System.out.println(lengthOfLongestSubstring(s4));
        System.out.println(lengthOfLongestSubstring(s5));

    }

    /**
     * @param s
     * @return
     */
    public static int lengthOfLongestSubstring(String s) {

        HashMap<Character, Integer> map = new HashMap<Character, Integer>();

        int begin = 0, maxLength = 0;
        for (int end = 0; end < s.length(); end++) {
            Character character = s.charAt(end);
            if (!map.containsKey(character)) {
                map.put(character, 1);
            } else {
                map.put(character, map.get(character) + 1);
            }

            if (map.get(character) == 2) {
                while (map.get(s.charAt(begin)) <= 1) {
                    map.put(s.charAt(begin), map.get(s.charAt(begin)) - 1);
                    begin++;
                }
                map.put(s.charAt(begin), map.get(s.charAt(begin)) - 1);
                begin++;
            }
            if ((end - begin + 1) >= maxLength) {
                maxLength = end - begin + 1;
            }
        }

        return maxLength;
    }
}