Find longest substring without repeating characters

Question

Given a string S of length N find longest substring without repeating characters.

Example:

Input:

Answer 1

We can consider all substrings one by one and check for each substring whether it contains all unique characters or not. There will be n*(n+1)/2 substrings. Whether a substirng contains all unique characters or not can be checked in linear time by scanning it from left to right and keeping a map of visited characters. Time complexity of this solution would be O(n^3).`

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;


public class LengthOfLongestSubstringWithOutRepeatingChar {
	public static void main(String[] args)
	{
	String s="stackoverflow";	
	//allSubString(s);
	System.out.println("result of find"+find(s));
	}
	public static String find(String s)
	{
		List allSubsring=allSubString(s);
		Set main =new LinkedHashSet();
		for(String temp:allSubsring)
		{
			boolean a = false;
			for(int i=0;ii;k--)
				{
					if(temp.charAt(k)==temp.charAt(i))
						a=true;
				}
			}
			if(!a)
			{
				main.add(temp);
			}
		}
		/*for(String x:main)
		{
		System.out.println(x);	
		}*/
		String res=null;
		int min=0,max=s.length();
		for(String temp:main)
		{
		if(temp.length()>min&&temp.length() allSubString(String str) {
	List all=new ArrayList();
	int c=0;
	for (int i = 0; i < str.length(); i++) {
		for (int j = 0; j <= i; j++) {
			if (!all.contains(str.substring(j, i + 1)))
			{
				c++;
				all.add(str.substring(j, i + 1));
			}
		}
	}
	for(String temp:all)
	{
		System.out.println("substring :-"+temp);
	}
	System.out.println("count"+c);
	return all;
}
}