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Commit 88d9ea8

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🐱(string): 3. 无重复字符的最长子串
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‎docs/data-structure/string/README.md‎

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@@ -76,7 +76,34 @@ if __name__ == '__main__':
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[原题链接](https://leetcode-cn.com/problems/longest-substring-without-repeating-characters/solution/)
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### 思路
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### 解一:暴力求解
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```python
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class Solution:
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def lengthOfLongestSubstring(self, s: str) -> int:
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length = len(s)
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ans = 0
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for i in range(length):
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tmp = 1
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nums = dict()
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nums[s[i]] = True
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for j in range(i + 1, length):
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c = s[j]
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if c in nums:
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# 已经存在
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break
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else:
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# 不存在,继续
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tmp += 1
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nums[c] = True
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ans = max(ans, tmp)
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return ans
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```
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- 时间复杂度:`O(n^2)`
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- 空间复杂度:`O(m)`
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### 解二
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- 用 hash 记录每个字符出现的位置
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- 当前字符:
@@ -108,6 +135,28 @@ class Solution(object):
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return max_length
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```
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2020年05月02日 复盘:
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```python
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class Solution:
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def lengthOfLongestSubstring(self, s: str) -> int:
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ans = 0
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# 滑动窗口,左侧:start,右侧:i
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start = 0
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length = len(s)
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# 记录字符所在下标
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nums = dict()
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for i in range(length):
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cur_c = s[i]
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# print(start)
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if cur_c in nums:
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if nums[cur_c] >= start:
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start = nums[cur_c] + 1
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# 替换字符所在位置
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nums[cur_c] = i
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ans = max(ans, i - start + 1)
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return ans
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```
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## 6. Z 字形变换
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