剑指 Offer 48. 最长不含重复字符的子字符串

import java.util.HashMap;
import java.util.Map;

class Solution {

    public int lengthOfLongestSubstring(String s) {

        int res = 0;
        int len = 0;
        int idx = 0;

        // 某个字符 + 出现位置
        Map<Character, Integer> map = new HashMap<>();
        Map<Integer, Character> map1 = new HashMap<>();

        for(int i=0; i<s.length(); i++){

            if(!map.containsKey(s.charAt(i))){
                map.put(s.charAt(i), i);
                map1.put(i, s.charAt(i));
                len += 1;
            }else {
                res = Math.max(len, res);
                int index = map.get(s.charAt(i));

                for(int j = idx; j <= index; j++){
                    map.remove(map1.get(j));
                    map1.remove(j);
                }
                idx = index+1;
                len = i - index;
                map.put(s.charAt(i), i);
                map1.put(i, s.charAt(i));
            }
        }

        res = Math.max(len, res);
        return res;
    }

    public static void main(String[] args) {
        Solution s = new Solution();

        s.lengthOfLongestSubstring("pwwkew");
    }
}

每次遇到重复的值的时候，去取现在取到的最大值就可以啦！