leetcode_3 Longest Substring Without Repeating Characters

Given a string, find the length of the longest substring without repeating characters.
Example 1:
Input: “abcabcbb”
Output: 3
Explanation: The answer is “abc”, with the length of 3.
Example 2:
Input: “bbbbb”
Output: 1
Explanation: The answer is “b”, with the length of 1.
Example 3:
Input: “pwwkew”
Output: 3
Explanation: 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.

solution

1. Double cycle of violence

public static int lengthOfLongestSubstring(String s) {
        char[] chars = s.toCharArray();
        Set<Character> set = new HashSet<>();
        int max = 0;
        int temp = 0;
        for (int index = 0 ;index < chars.length; index ++) {
            for (int i = index; i < chars.length; i++) {
                if (set.add(chars[i])) {
                    temp++;
                    if(i == (chars.length -1)){
                        max = max < temp ? temp : max;
                    }
                } else {
                    max = max < temp ? temp : max;
                    temp = 0;
                    set = new HashSet<>();
                    break;
                }
            }
        }
        return max;
    }

2.hashMap do sentenced to heavy container

public static int lengthOfLongestSubstring2(String s) {
        char[] chars = s.toCharArray();
        Map<Character,Integer> map = new HashMap<>();
        int max = 0;
        for (int i = 0; i < chars.length; i++) {
            // 不包含则添加进去
            if (!map.containsKey(chars[i])) {
                map.put(chars[i], i);
                if (i == (chars.length - 1)) {
                    max = map.size() > max ? map.size(): max;
                }
            } else {
                max = max = map.size() > max ? map.size(): max;
                i = map.get(chars[i]);
                map = new HashMap<>();
            }
        }
        return max;
    }