3. Longest Substring Without Repeating Characters

QUESITON:

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 subsequenceand not a substring.

EXPLANATION:

算法相当于一个list，然后往里面不停的加东西，如果有重复的，就把重复的地方截取出来作为新的list。

SOLUTION:

class Solution {
    public int lengthOfLongestSubstring(String s) {
        if(s.length()<=1) return s.length();
        char[] chars = s.toCharArray();
        List<Character> list = new ArrayList<>();
        int result = 0;
        for(int i = 0;i<chars.length;i++){
            int index = list.indexOf(chars[i]);
            list.add(chars[i]);
            if(index==-1){
                result = Math.max(result,list.size());
            }else {
                ArrayList<Character> tmplist =new ArrayList<>();
                for(int j = list.size()-1;j>index;j--){
                    tmplist.add(0,list.get(j));
                }
                list = tmplist;
                result = Math.max(result,list.size());
            }

        }
        return result;
    }
}

class Solution(object):
    def lengthOfLongestSubstring(self, s):
        """
        :type s: str
        :rtype: int
        """
        tmp = ""
        result = 0
        for i in range(0,len(s),):
            index = tmp.find(s[i])
            tmp = tmp+s[i]
            if index != -1 :
                tmp = tmp[index+1:]
            result = max(result,len(tmp))
        return result
--> return <--