LongestSubstring.java

import java.util.HashMap;

public class LongestSubstring {
    public static int longest(String str) {
        HashMap<Character, Integer> alpha = new HashMap<>();
        int start = 0;
        int end = 0;
        int max = Integer.MIN_VALUE;
        for (int i = 0; i < str.length(); i++) {
            if (alpha.get(str.charAt(i)) == null) {
                alpha.put(str.charAt(i), i);
                end++;
            } else {
                // System.out.println("Start: " + start + " End: " + end + " Count: " + (end - start) + " String: " + str.substring(start + 1, end));
                if (max < end - start) {
                    max = end - start;
                }
                start = i;
                end = i;
                i = alpha.get(str.charAt(i));
                alpha.clear();
            }
        }
        return max > end - start ? max : end - start;
    }

    public static void main(String[] args) {
        System.out.println(longest("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"));
    }
}