leetcode_3_Longest_Substring_Without_Repeating_Characters

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 asubstring, "pwke" is a subsequence and not a substring.

这个题就是求最小不重复的子字符串

代码如下：

class Solution(object):    def lengthOfLongestSubstring(self, s):        temp = result = ''        for i in s:            if i not in temp:                temp += i            else:                index = temp.index(i)                temp = temp[index + 1: ] + i            if len(result) < len(temp):                result = temp        return len(result) 思路是：
迭代字符串中的所有字符
如果不重复则依次将字符存入临时变量中
如果重复了则将重复字符串之前的字符移除并且加入当前字符，形成新字符串
然后对比是否之前得到最长字符串是最长的，如果不是则更新最长字符串
最后返回字符长度
时间复杂度O（n）官网有一个vote最多的python解是
class Solution:    # @return an integer    def lengthOfLongestSubstring(self, s):        start = maxLength = 0        usedChar = {}                for i in range(len(s)):            if s[i] in usedChar and start <= usedChar[s[i]]:                start = usedChar[s[i]] + 1            else:                maxLength = max(maxLength, i - start + 1)            usedChar[s[i]] = i        return maxLength
他的思路是和我相仿，时间复杂度和我一样，但是空间复杂度比我的高