LeetCode(3) - Longest Substring Without Repeating Characters

https://leetcode.com/problems/longest-substring-without-repeating-characters/#/description

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.

Solution:

整体思路是不断地记录唯一的char，当出现重复时，计算Length并清空记录。

由于用for来做，所以记得在最后的时候做最后的检测。

public int lengthOfLongestSubstring(String s) {
int maxLength = 0;

Set<Character> dict = new HashSet<>();
int start = 0;
char[] chars = s.toCharArray();
for(int i = 0; i < chars.length; i++) {
if(!dict.add(chars[i])) {
int length = i - start;
if(length > maxLength) {
maxLength = length;
}

start = i;
dict.clear();
}
}

//last check
maxLength = maxLength > s.length() - start ? maxLength : s.length() - start;

return maxLength;
}