Leetcode 3. Longest Substring without repeating characters (Python version)

Topic:

Given a string, find the length of the longest substring without repeating characters. For example, the longest substring without repeating letters for "ABCABCBB" are "abc", which the length is 3. For "bbbbb" the longest substring are "B", with the length of 1.

The main idea is to find the longest non-repeating substring

Algorithm ideas:

This problem should be able to use dynamic programming, I use a double point method

One pointer start pointing to the substring header, the other pointer end pointing to the tail of the substring

Increments end each time to determine whether the character in the end is present in the current substring.

• • If it appears, move the start pointer backward one

  • Otherwise, move the end pointer backwards and update the oldest string length

Finally, the maximum length of the substring is returned.

The algorithm can be optimized when the start pointer is moved, but I find that the result is not changed after optimization, just stick to the original code.

Code:

Class solution (object):     def lengthoflongestsubstring (self, s):          "" "        :type s:  str        :rtype: int          "" "        slen = len (s)          if sLen == 0 or sLen == 1:             return sLen         letters = list (s)         hashSet = {}         hashSet[letters[0]] = 1         start = 0        end = 1       &nBsp; maxlen = 1        while end != slen :            letter = letters[end]             if hashset.has_key (letter)  and  hashSet[letter] > 0:                 hashSet[letters[start]] -= 1                 start += 1                 continue             hashSet[letter] = 1             end += 1             if end - start > maxLen:                 maxLen = end - start         return maxlen

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Leetcode 3. Longest Substring without repeating characters (Python version)