Given a string, find the length of the longest substring without repeating characters.
Examples:
Given "abcabcbb", the answer is "abc", which the length is 3.
Given "bbbbb", the answer is "b", with the length of 1.
Given "pwwkew", the answer is "wke", with the length of 3. Note that the answer must be a substring, "pwke" is a subsequence and not a substring.
class Solution {
public int lengthOfLongestSubstring(String s) {
if(s == null){
return 0;
}
char[] sc = s.toCharArray();
if(sc.length > 1){
return countLongestSubstring(sc);
}
return sc.length;
}
/**
* counter longest substring
*/
private int countLongestSubstring(char[] sc){
// current save substring list
List<Character> currentSubstring = new ArrayList<>();
// longest substring list
List<Character> longestSubstring = new ArrayList<>();
// flag index
int flagIndex = 0;
for (int i = 0;i < sc.length; i++) {
char item = sc[i];
if (!currentSubstring.contains(item)) {
// add to list
currentSubstring.add(item);
} else {
if (longestSubstring.size() < currentSubstring.size()) {
// evalution value
longestSubstring = currentSubstring;
}
// judge index
if(flagIndex < sc.length -1){
i = flagIndex + 1;
flagIndex = i;
item = sc[i];
}
// init value
currentSubstring = new ArrayList<>();
currentSubstring.add(item);
}
}
if (longestSubstring.size() < currentSubstring.size()) {
// evalution value
longestSubstring = currentSubstring;
}
// return result
return longestSubstring.size();
}
}