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.

lengthOfLongestSubstring.java

import java.util.*;

public class Solution {
    public int lengthOfLongestSubstring(String s) {
        // Start typing your Java solution below
        // DO NOT write main() function
        int count = 0;
        int max = 0;
        int startIndex = 0;
        int endIndex = 0;
        HashMap<Character, Integer> table = new HashMap<Character, Integer>();
        int size = s.length();
        for(int i = 0; i < size; i++) {
            if(!table.containsKey(s.charAt(i))) {
                count++;
                table.put(s.charAt(i), i);
            } else {
                if (count > max) {
                    max = count;
                }
                // deal with the case for axefgxhi when x is duliplicated.
                endIndex = table.get(s.charAt(i));
                for(int j = endIndex; j >= startIndex; j--) {
                    table.remove(s.charAt(j));
                    count--;
                }
                table.put(s.charAt(i), i);
                count++;
                startIndex = endIndex + 1;
            }
        }
        if (count > max) {
            max = count;
        }
        return max;
    }
}