LeetCode 003 Longest Substring Without Repeating Characters

package ywheel.leetcode._003_longest_substring_without_repeating_characters;/** * Given a string, find the length of the longest substring without repeating * characters. For example, the longest substring without repeating letters for * "abcabcbb" is "abc", which the length is 3. For "bbbbb" the longest substring * is "b", with the length of 1. *  * @author ywheel *  */public class LongestSubString {    public int lengthOfLongestSubstring(String s) {        if (s == null || s.isEmpty()) {            return 0;        }        int maxLength = 0;        int[] index = new int[256];        for (int i = 0; i < 256; i++) {            index[i] = -1;        }        int strLen = s.length();        int length = 1;        index[s.charAt(0)] = 0;        for (int i = 1; i < strLen; i++) {            char ch = s.charAt(i);            if (i - index[ch] <= length) {                // repeat                maxLength = length > maxLength ? length : maxLength;                length = i - index[ch];            } else {                length++;            }            index[ch] = i; // set the last index of ch        }        maxLength = length > maxLength ? length : maxLength;        return maxLength;    }    public static void main(String[] args) {        LongestSubString solution = new LongestSubString();        String s = "abcabcbb";        System.out.println(solution.lengthOfLongestSubstring(s));        s = "bbbbbb";        System.out.println(solution.lengthOfLongestSubstring(s));    }}