3｜无重复字符的最长子串

https://leetcode-cn.com/problems/longest-substring-without-repeating-characters/
点击查看【bilibili】

class Solution(object):
    def lengthOfLongestSubstring(self, s):
        # 定义左右指针
        left = 0
        right = 0
        # 定义输出的最大长度
        max = 0
        # 定义一个字典来存储当前字符串
        window = dict()
        while right < len(s):
            current_char = s[right]
            # .setdefault()
            # 如果键不存在于字典中，将会添加键并将值设为默认值。
            window.setdefault(current_char, 0)
            window[current_char] += 1
            # 往后走一位
            right += 1
            # 窗口中有重复字符时缩小窗口
            while window[current_char] > 1:
                left_char = s[left]
                # i往右移动一位
                left += 1
                # 更新字典中 current_char 的数量
                window[left_char] -= 1
                window_size = right - left
                if window_size > max:
                    max = window_size 
        return max