LeetCode:Longest Substring Without Repeating Characters

Longest Substring Without Repeating Characters
Total Accepted: 152787 
Total Submissions: 687012 
Difficulty: Medium
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.
Subscribe to see which companies asked this question
Hide Tags
 
Hash Table Two Pointers String
Hide Similar Problems
 
(H) Longest Substring with At Most Two Distinct Characters
考え方:
1つのHashMapが各文字を格納する位置を維持します.2つのポインタi,jは、最長子列の範囲を維持する.
java code:

public class Solution {
    public int lengthOfLongestSubstring(String s) {
        
        if(s==null || s.length()==0) return 0;
        Map<Character, Integer> map = new HashMap<Character, Integer>();
        int max = 0;
        for(int i=0,j=0;i<s.length();i++) {
            char c = s.charAt(i);
            if(map.containsKey(c)) {
                j = Math.max(j, map.get(c)+1);
            }
            map.put(c, i);
            max = Math.max(max, i-j+1);
        }
        return max;
    }
}