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LeetCode 131. Palindrome Partitioning
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‎README.md

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| [127. Word Ladder][lc127] | 🔴 Hard | [![python](res/py.png)][lc127py] |
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| [128. Longest Consecutive Sequence][lc128] | 🟠 Medium | [![python](res/py.png)][lc128py] |
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| [130. Surrounded Regions][lc130] | 🟠 Medium | [![python](res/py.png)][lc130py] |
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| [131. Palindrome Partitioning][lc131] | 🟠 Medium | [![python](res/py.png)][lc131py] |
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| [133. Clone Graph][lc133] | 🟠 Medium | [![python](res/py.png)][lc133py] |
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| [134. Gas Station][lc134] | 🟠 Medium | [![python](res/py.png)][lc134py] |
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| [135. Candy][lc135] | 🔴 Hard | [![python](res/py.png)][lc135py] |
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[lc128py]: leetcode/longest-consecutive-sequence.py
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[lc130]: https://leetcode.com/problems/surrounded-regions/
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[lc130py]: leetcode/surrounded-regions.py
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[lc131]: https://leetcode.com/problems/palindrome-partitioning/
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[lc131py]: leetcode/palindrome-partitioning.py
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[lc133]: https://leetcode.com/problems/clone-graph/
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[lc133py]: leetcode/clone-graph.py
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[lc134]: https://leetcode.com/problems/gas-station/

‎leetcode/lists/dp.md

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| | Level | Name | Solutions |
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| :-: | --------- | ------------------------------------------------------------------------- | --------------------------------------- |
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| ✅ | 🟢 Easy | [392. Is Subsequence][lc392] | [![python](../../res/py.png)][lc392py] |
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| | 🟠 Medium | [131. Palindrome Partitioning][lc131] | |
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| ✅ | 🟠 Medium | [131. Palindrome Partitioning][lc131] | [![python](../../res/py.png)][lc131py] |
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| ✅ | 🟠 Medium | [139. Word Break][lc139] | [![python](../../res/py.png)][lc139py] |
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| | 🟠 Medium | [467. Unique Substrings in Wraparound String][lc467] | |
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| | 🟠 Medium | [712. Minimum ASCII Delete Sum for Two Strings][lc712] | |
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[lc392]: https://leetcode.com/problems/is-subsequence/
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[lc392py]: ../is-subsequence.py
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[lc131]: https://leetcode.com/problems/palindrome-partitioning/
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[lc131py]: ../palindrome-partitioning.py
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[lc139]: https://leetcode.com/problems/word-break/
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[lc139py]: ../word-break.py
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[lc467]: https://leetcode.com/problems/unique-substrings-in-wraparound-string/

‎leetcode/lists/neetcode.md

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> Get stuck? I've created a thorough 🎥 video explanation for each problem.
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- [Neetcode categorized list of problems](#neetcode-categorized-list-of-problems)
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- [Arrays & Hashing](#arrays--hashing)
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- [Arrays \& Hashing](#arrays--hashing)
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- [Two Pointers](#two-pointers)
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- [Sliding Window](#sliding-window)
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- [Stack](#stack)
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- [2-D Dynamic Programming](#2-d-dynamic-programming)
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- [Greedy](#greedy)
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- [Intervals](#intervals)
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- [Math & Geometry](#math--geometry)
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- [Math \& Geometry](#math--geometry)
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- [Bit Manipulation](#bit-manipulation)
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## Arrays & Hashing
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## Backtracking
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| | B75 | Level | Problem | Solutions |
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| :-: | --- | --------- | ------------------------------------------------- | ------------------------------------- |
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| ✅ | | 🟠 Medium | [78. Subsets][lc78] | [![python](../../res/py.png)][lc78py] |
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| ✅ | | 🟠 Medium | [39. Combination Sum][lc39] | [![python](../../res/py.png)][lc39py] |
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| ✅ | | 🟠 Medium | [46. Permutations][lc46] | [![python](../../res/py.png)][lc46py] |
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| ✅ | | 🟠 Medium | [90. Subsets II][lc90] | [![python](../../res/py.png)][lc90py] |
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| ✅ | ⭐ | 🟠 Medium | [40. Combination Sum II][lc40] | [![python](../../res/py.png)][lc40py] |
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| ✅ | ⭐ | 🟠 Medium | [79. Word Search][lc79] | [![python](../../res/py.png)][lc79py] |
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| | | 🟠 Medium | [131. Palindrome Partitioning][lc131] | |
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| ✅ | | 🟠 Medium | [17. Letter Combinations of a Phone Number][lc17] | [![python](../../res/py.png)][lc17py] |
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| ✅ | | 🔴 Hard | [51. N-Queens][lc51] | [![python](../../res/py.png)][lc51py] |
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| | B75 | Level | Problem | Solutions |
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| :-: | --- | --------- | ------------------------------------------------- | -------------------------------------- |
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| ✅ | | 🟠 Medium | [78. Subsets][lc78] | [![python](../../res/py.png)][lc78py] |
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| ✅ | | 🟠 Medium | [39. Combination Sum][lc39] | [![python](../../res/py.png)][lc39py] |
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| ✅ | | 🟠 Medium | [46. Permutations][lc46] | [![python](../../res/py.png)][lc46py] |
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| ✅ | | 🟠 Medium | [90. Subsets II][lc90] | [![python](../../res/py.png)][lc90py] |
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| ✅ | ⭐ | 🟠 Medium | [40. Combination Sum II][lc40] | [![python](../../res/py.png)][lc40py] |
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| ✅ | ⭐ | 🟠 Medium | [79. Word Search][lc79] | [![python](../../res/py.png)][lc79py] |
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| ✅ | | 🟠 Medium | [131. Palindrome Partitioning][lc131] | [![python](../../res/py.png)][lc131py] |
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| ✅ | | 🟠 Medium | [17. Letter Combinations of a Phone Number][lc17] | [![python](../../res/py.png)][lc17py] |
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| ✅ | | 🔴 Hard | [51. N-Queens][lc51] | [![python](../../res/py.png)][lc51py] |
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[lc78]: https://leetcode.com/problems/subsets/
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[lc78py]: ../subsets.py
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[lc79]: https://leetcode.com/problems/word-search/
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[lc79py]: https://leetcode.com/problems/word-search/
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[lc131]: https://leetcode.com/problems/palindrome-partitioning/
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[lc131py]: ../palindrome-partitioning.py
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[lc17]: https://leetcode.com/problems/letter-combinations-of-a-phone-number/
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[lc17py]: ../letter-combinations-of-a-phone-number.py
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[lc51]: https://leetcode.com/problems/n-queens/

‎leetcode/palindrome-partitioning.py

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# 131. Palindrome Partitioning
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# 🟠 Medium
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#
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# https://leetcode.com/problems/palindrome-partitioning/
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#
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# Tags: String - Dynamic Programming - Backtracking
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import timeit
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from typing import List
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# Classic backtracking solution, for each index, we try all string
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# prefixes to see if they are a palindrome, if they are, we use them to
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# build one of the solutions (one of the ways to partition the input
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# string) and keep building starting at the first unused index.
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#
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# Time complexity: O(n*2^n) - The decision tree splits in 2 at each
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# level, and there are n levels where n is the number of characters in
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# the input string. At each call, we iterate over all characters in
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# the substring, which could also be n, to check if the substring is
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# a palindrome.
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# Space complexity: O(n) - The height of the call stack, if we take into
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# consideration the result, then n^2 which is the possible number of
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# palindromes.
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#
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# Runtime 658 ms Beats 85.74%
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# Memory 30.3 MB Beats 47.4%
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class Solution:
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def partition(self, s: str) -> List[List[str]]:
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res, current = [], []
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# The first index that we need to look into.
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def bt(idx: int) -> None:
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if idx == len(s):
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res.append(current[:])
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# Try to form palindromes of all lengths starting at the
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# given index.
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for i in range(idx, len(s)):
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# Try to form a palindrome with i + 1 characters.
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sub = s[idx : i + 1]
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# If this substring is not a palindrome, ignore it.
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if sub == sub[::-1]:
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current.append(sub)
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bt(i + 1)
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current.pop()
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bt(0)
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return res
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def test():
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executors = [Solution]
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tests = [
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["a", [["a"]]],
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["aab", [["a", "a", "b"], ["aa", "b"]]],
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]
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for executor in executors:
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start = timeit.default_timer()
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for _ in range(1):
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for col, t in enumerate(tests):
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sol = executor()
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result = sol.partition(t[0])
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exp = t[1]
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assert result == exp, (
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f"\033[93m» {result} <> {exp}\033[91m for"
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+ f" test {col} using \033[1m{executor.__name__}"
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)
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stop = timeit.default_timer()
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used = str(round(stop - start, 5))
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cols = "{0:20}{1:10}{2:10}"
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res = cols.format(executor.__name__, used, "seconds")
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print(f"\033[92m» {res}\033[0m")
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test()

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