18, Longest Substring Without Repeating Characters.java

/*
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.
*/
class Solution {
    public int lengthOfLongestSubstring(String s) {
        HashMap<Character,Integer>map=new HashMap<Character,Integer>();
        int left=0;
        int right=0;
        int n= s.length();
        int len=0;
        while(right<n){
            if(map.containsKey(s.charAt(right)))
                left=Math.max(map.get(s.charAt(right))+1,left);
            
        map.put((s.charAt(right)),right);
        len=Math.max(len,right-left+1);
        right++;
        }
        
        return len;
        
    }
}