30 lines
973 B
Python
30 lines
973 B
Python
# Time: O(N)
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# Space: O(N)
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class Solution:
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def lengthOfLongestSubstring(self, s: str) -> int:
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'''
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Sliding-window approach
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'''
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# Keep a track of unique chars we've seen so far in the substring
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# we are looking at
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seen = set()
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start, end = 0, 0
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maxl = 0
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while start <= end < len(s):
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# Our current substring is denoted by their bounds [start, end]
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# If we see a char in `end` which is already seen by us, we need
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# to keep moving `start` until we are left with a new character
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while s[end] in seen:
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# Since `start` is moving up, we need to remove existing
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# `start` char from the set if it exists
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seen.remove(s[start])
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start += 1
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seen.add(s[end])
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maxl = max(maxl, (end - start) + 1)
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end += 1
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return maxl
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