[LeetCode][python3]0003. Longest Substring Without Repeating Characters

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N2I -2020.03.15

1. My first solution

class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        
        if not s:
            return 0
        dic={}
        stuck=0
        output=1
        for index,item in enumerate(s):
            if item not in dic:
                dic[item]=index
            else:
                output=max(output,index-stuck)
                stuck=max(dic[item]+1,stuck)
                dic[item]=index
        output=max(output,len(s)-stuck)
        return output
 

2. A better solution

class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        dicts = {}
        maxlength = start = 0
        for i,value in enumerate(s):
            if value in dicts:
                sums = dicts[value] + 1
                if sums > start:
                    start = sums
            num = i - start + 1
            if num > maxlength:
                maxlength = num
            dicts[value] = i
        return maxlength
 

Explanation:
Most of them are the same with my answer. Which start replaced by stuck (cause the duplicate char stuck the string to be longer in my words). Biggest different in using Max() function, not using it may low down your cost.