LeetCode 3. 无重复字符的最长子串

3. 无重复字符的最长子串

解题思路

双指针 + 哈希表

参考代码

class Solution {
    public int lengthOfLongestSubstring(String s) {
        Map<Character, Integer> map = new HashMap<>();
        int left = 0, right = 0;
        int maxLen = 0;

        while(right < s.length()) {
            char c = s.charAt(right);
            map.put(c, map.getOrDefault(c, 0) + 1);
            right ++;

            while(map.get(c) > 1) {
                char leftChar = s.charAt(left);
                map.put(leftChar, map.get(leftChar) - 1);
                left ++;
            }

            maxLen = Math.max(maxLen, right - left);
        }
        return maxLen;
    }
}