[LeetCode] 3. Longest Substring Without Repeating Characters (Java)

Description

Given a string s, find the length of the longest substring without repeating characters.

 

반복되는 문자가 없는 가장 긴 문자열의 길이를 구하라.

 

Example 1:

Input: s = "abcabcbb"
Output: 3
Explanation: The answer is "abc", with the length of 3.

Example 2:

Input: s = "bbbbb"
Output: 1
Explanation: The answer is "b", with the length of 1.

Example 3:

Input: s = "pwwkew"
Output: 3
Explanation: The answer is "wke", with the length of 3.
Notice that the answer must be a substring, "pwke" is a subsequence and not a substring.

 

Constraints:

• 0 <= s.length <= 5 * 104
• s consists of English letters, digits, symbols and spaces

Solution

public class Solution {
    public int lengthOfLongestSubstring(String s) {
        int maxLength = 0;
        int i=0, j=0;
        int length = s.length();
        HashSet<Character> set = new HashSet<>();

        while (j < length) {
            if(i > j){
                break;
            }
            if (!set.contains(s.charAt(j))){
                set.add(s.charAt(j++));
                maxLength = Math.max(maxLength, j - i);
                continue;
            }
            set.remove(s.charAt(i++));
        }
        return maxLength;
    }
}

j번째 문자부터 반복되지 않는 문자열까지의 길이를 구하여 Math.max()로 가장 큰 값을 구한다.