lengthOfLongestSubstring.java

// Java program to find the length of the
// longest substring without repeating
// characters
import java.io.*;
import java.util.*;
 
class sk{
 
// This function returns true if all characters in
// str[i..j] are distinct, otherwise returns false
public static Boolean areDistinct(String str,
                                  int i, int j)
{
     
    // Note : Default values in visited are false
    boolean[] visited = new boolean[26];
 
    for(int k = i; k <= j; k++)
    {
        if (visited[str.charAt(k) - 'a'] == true)
            return false;
             
        visited[str.charAt(k) - 'a'] = true;
    }
    return true;
}
 
// Returns length of the longest substring
// with all distinct characters.
public static int longestUniqueSubsttr(String str)
{
    int n = str.length();
     
    // Result
    int res = 0;
     
    for(int i = 0; i < n; i++)
        for(int j = i; j < n; j++)
            if (areDistinct(str, i, j))
                res = Math.max(res, j - i + 1);
                 
    return res;
}
 
// Driver code
public static void main(String[] args)
{
    String str = "geeksforgeeks";
    System.out.println("The input string is " + str);
 
    int len = longestUniqueSubsttr(str);
     
    System.out.println("The length of the longest " +
                       "non-repeating character " +
                       "substring is " + len);
}
}