LongestSubstringWithoutRepeatingCharBest

/**
 * 	@INPUT  :::String str = "ABCDABDEHHHFGCABD";
 * @OUTPUT
 *String is ::HFGCABD
 lenth of LongestSubsting ::: 7
Complexity will be O(n) and single scan
 */
import java.util.HashSet;

public class LongestSubstringWithoutRepeatingCharBest {

	public static void main(String[] args) {
		String str = "ABCDABDEHHHFGCABD";

		System.out.println("lent of LongestSubsting ::: "
				+ longestSubString(str));

	}

	private static int longestSubString(String str) {

		HashSet<Character> hset = new HashSet<>();

		int n = str.length();
		int max = 0;
		int startString = 0;
		for (int i = 0; i < n; i++) {
			int j = i;
			int an = 0;
			startString = i;

			while (j < n && hset.add(str.charAt(j))) {

				j++;
				an++;
			}

			max = Math.max(max, an);
			startString = an;
			hset.clear();
		}

		System.out.println("String is ::"
				+ str.substring(startString, startString + max));

		return max;
	}

}