Find longest substring without repeating characters

Question

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

Example:

Input:

Answer 1

EDITED:

following is an implementation of the concesus. It occured to me after my original publication. so as not to delete original, it is presented following:

public static String longestUniqueString(String S) {
    int start = 0, end = 0, length = 0;
    boolean bits[] = new boolean[256];
    int x = 0, y = 0;
    for (; x < S.length() && y < S.length() && length < S.length() - x; x++) {
        bits[S.charAt(x)] = true;
        for (y++; y < S.length() && !bits[S.charAt(y)]; y++) {
            bits[S.charAt(y)] = true;
        }
        if (length < y - x) {
            start = x;
            end = y;
            length = y - x;
        }
        while(y

ORIGINAL POST:

Here is my two cents. Test strings included. boolean bits[] = new boolean[256] may be larger to encompass some larger charset.

public static String longestUniqueString(String S) {
    int start=0, end=0, length=0;
    boolean bits[] = new boolean[256];
    int x=0, y=0;
    for(;x