Algorithm
3. Longest Substring Without Repeating Characters
Description
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.
Example 4:
Input: s = ""
Output: 0
Constraints:
- 0 <= s.length <= 5 * 104
- s consists of English letters, digits, symbols and spaces.
Solution
class Solution {
public int lengthOfLongestSubstring(String s) {
if(s==null||s.length()==0){
return 0;
}
int max = 0;
Map<Character,Integer> map = new HashMap<>();
for(int i=0,j=0;i<s.length();i++){
if(map.containsKey(s.charAt(i))){
j = Math.max(j, map.get(s.charAt(i))+1);
}
map.put(s.charAt(i), i);
max = Math.max(max, i-j+1);
}
return max;
}
}
