Longest Substring Without Repeating Characters

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

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.

Solution

class Solution {

public int lengthOfLongestSubstring(String s) {

int n = s.length();

int maxLength = 0;

Map<Character, Integer> charMap = new HashMap<>();

int left = 0;

for (int right = 0; right < n; right++) {

if (!charMap.containsKey(s.charAt(right)) || charMap.get(s.charAt(right)) < left) {

charMap.put(s.charAt(right), right);

maxLength = Math.max(maxLength, right - left + 1);

} else {

left = charMap.get(s.charAt(right)) + 1;

charMap.put(s.charAt(right), right);

}

}

return maxLength;

}

}