package edu.bupt.cici.leetcode;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;

public class LongestSubstringWithoutRepeatingCharacters {

    public int lengthOfLongestSubstring(String s) {
        if (s == null && s.length() == 0)
            return 0;
        HashSet<Character> set = new HashSet<Character>();
        int max = 0;
        int walker = 0;
        int runner = 0;
        while (runner < s.length()) {
            if (set.contains(s.charAt(runner))) {
                if (max < runner - walker) {
                    max = runner - walker;
                }
                while (s.charAt(walker) != s.charAt(runner)) {
                    set.remove(s.charAt(walker));
                    walker++;
                }
                walker++;
            } else {
                set.add(s.charAt(runner));
            }
            runner++;
        }
        max = Math.max(max, runner - walker);
        return max;
    }

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        LongestSubstringWithoutRepeatingCharacters sol = new LongestSubstringWithoutRepeatingCharacters();
        String s = "abcaaaaabcd";
        System.out.println(sol.lengthOfLongestSubstring(s));

    }

}