Skip to content

Add solution for 3rd LeetCode Practice Problem - Longest Substring Without Repeating Characters #184

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 5 commits into from
Aug 2, 2021
Merged

Add solution for 3rd LeetCode Practice Problem - Longest Substring Without Repeating Characters #184

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
1b17661
Add solution for 3rd LeetCode Practice Problem - Longest Substring Wi…
Git-Harshit Aug 1, 2021
8b1987a
Update README.md
Git-Harshit Aug 1, 2021
922745d
Rename 3. Longest Substring Without Repeating Characters.py to Longes…
Git-Harshit Aug 1, 2021
09da6fc
Merge branch 'codedecks-in:master' into master
Git-Harshit Aug 2, 2021
172059c
Fix Longest_Substring_Without_Repeating_Characters solution link
Git-Harshit Aug 2, 2021
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
29 changes: 29 additions & 0 deletions Python/Longest_Substring_Without_Repeating_Characters.py
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,29 @@
"""
LeetCode submission result:
(987 / 987 test cases passed. \ Status: Accepted \ Runtime: 76 ms \ Memory Usage: 14.4 MB)
- available at: https://leetcode.com/submissions/detail/531509506/
"""

class Solution:
def lengthOfLongestSubstring(self, string: str) -> int:

# Creating a charactersCountDict to store count of characters in the current
charactersCountDict = {}

# declaring variables to mark the Starting Index as well as Maximum Length of any contiguous substring without recurring characters achieved
currentStartingIndex = maxLength = 0

# Iterating through all indices of the string, one by one, while analyzing string between 'currentStartingIndex' and this ending 'index'.
for index in range(len(string)):
# In case string character at this index already exists between string[currentStartingIndex:index], then removing the starting of string from currentStartingIndex considered to remove any repeated characters in the considered string
while string[index] in charactersCountDict:
charactersCountDict[string[currentStartingIndex]] -= 1 # Reducing the string character count of string[currentStartingIndex] character so as to eliminate it from current string (in the considered sliding window)
if charactersCountDict[string[currentStartingIndex]] < 1: charactersCountDict.pop(string[currentStartingIndex]) # If current count of this character goes below 1, that means this character no longer exists in the substring, therefore the character key is removed from charactersCountDict counter dictionary
currentStartingIndex += 1 # Shifting the currentStartingIndex one step ahead

# Now that the while loop has completed, it is assured that this character is not included in the substring string[currentStartingIndex:index], therefore we can safely insert it in string[currentStartingIndex:index+1] (last index excluded in the string slice)
charactersCountDict[string[index]] = 1

maxLength = max(maxLength, index-currentStartingIndex+1) # Assessing maxLength to be maximum of current substring with unique character and maximum length achieved at any point of time while carefully sliding the limits

return maxLength # Finally, returning the desired maximum length of contiguous substring that has no repeating characters
15 changes: 8 additions & 7 deletions README.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -156,18 +156,19 @@ Check out ---> [Sample PR](https://github.com/codedecks-in/LeetCode-Solutions/pu
# String

| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
| ---- | ----------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------- | ------ | ------ | ---------- | --- | --------------- |
| :--: | ----------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------- | ------ | ------ | ---------- | --- | --------------- |
| 3 | [Longest Substring Without Repeating Characters](https://leetcode.com/problems/longest-substring-without-repeating-characters/) | [Python](./Python/Longest_Substring_Without_Repeating_Characters.py) | _O(n)_ | _O(n)_ | Medium | `Hash Table`<br/>`Sliding Window` | Open for improvisation, mentioned time and space complexities unconfirmed |
| 8 | [String to Integer (atoi)](https://leetcode.com/problems/string-to-integer-atoi/) | [Java](./Java/string-to-integer-atoi.java) | _O(n)_ | _O(1)_ | Medium | | |
| 9 | [Palindrome Number](https://leetcode.com/problems/palindrome-number/) | [Java](./Java/palindrome-number.java) | _O(n)_ | _O(1)_ | Easy | | |
| 151 | [Reverse Words in a String](https://leetcode.com/problems/reverse-words-in-a-string/) | [Java](./Java/reverse-words-in-a-string.java) | _O(1)_ | _O(n)_ | Medium | | |
| 383 | [Ransom Note](https://leetcode.com/problems/ransom-note/) | [Java](./Java/ransom-note.java) | _O(1)_ | _O(n)_ | Easy | | Character Count |
| 387 | [First Unique Character in a String](https://leetcode.com/problems/first-unique-character-in-a-string/) | [Java](./Java/first-unique-character-in-a-string.java) | _O(n)_ | _O(1)_ | Easy | | Character Count |
| 151 | [Reverse Words in a String](https://leetcode.com/problems/reverse-words-in-a-string/) | [Java](./Java/reverse-words-in-a-string.java) | _O(1)_ | _O(n)_ | Medium | | |
| 520 | [Detect Capital Use](https://leetcode.com/problems/detect-capital/) | [Java](./Java/detect-capital-use.java) | _O(n)_ | _O(1)_ | Easy | | |
| 767 | [Reorganize String](https://leetcode.com/problems/reorganize-string/) | [Python](./Python/reorganize-string.py) | _O(n)_ | _O(n)_ | Medium | | |
| 859 | [Buddy Strings](https://leetcode.com/problems/buddy-strings/) | [Java](./Java/buddy-strings.java) | _O(n)_ | _O(1)_ | Easy | | |
| 1221 | [Split a String in Balanced Strings](https://leetcode.com/problems/split-a-string-in-balanced-strings/) | [Python](./Python/split-a-string-in-balanced-strings.py) | _O(n)_ | _O(1)_ | Easy | | |
| 1614 | [Maximum Nesting Depth of the Parentheses](https://leetcode.com/problems/maximum-nesting-depth-of-the-parentheses/) | [Java](./Java/max-nesting-depth-parentheses.java) | _O(n)_ | _O(1)_ | Easy | | |
| 1374 | [Generate a String With Characters That Have Odd Counts](https://leetcode.com/problems/generate-a-string-with-characters-that-have-odd-counts/) | [Java](./Java/generate-a-string-with-characters-that-have-odd-counts.java) | _O(n)_ | _O(1)_ | Easy | | |
| 859 | [Buddy Strings](https://leetcode.com/problems/buddy-strings/) | [Java](./Java/buddy-strings.java) | _O(n)_ | _O(1)_ | Easy | | |
| 9 | [Palindrome Number](https://leetcode.com/problems/palindrome-number/) | [Java](./Java/palindrome-number.java) | _O(n)_ | _O(1)_ | Easy | | |
| 767 | [Reorganize String](https://leetcode.com/problems/reorganize-string/) | [Python](./Python/reorganize-string.py) | _O(n)_ | _O(n)_ | Medium | | |
| 8 | [String to Integer (atoi)](https://leetcode.com/problems/string-to-integer-atoi/) | [Java](./Java/string-to-integer-atoi.java) | _O(n)_ | _O(1)_ | Medium | | |
| 1614 | [Maximum Nesting Depth of the Parentheses](https://leetcode.com/problems/maximum-nesting-depth-of-the-parentheses/) | [Java](./Java/max-nesting-depth-parentheses.java) | _O(n)_ | _O(1)_ | Easy | | |
<br/>
<div align="right">
<b><a href="#algorithms">⬆️ Back to Top</a></b>
Expand Down