added some python solutions

Author: Kurt-Yu

README.md

@@ -8,6 +8,7 @@ LeetCode
 
 | # | Title | Solution | Difficulty |
 |---| ----- | -------- | ---------- |
+|978|[Longest Turbulent Subarray](https://leetcode.com/problems/longest-turbulent-subarray/) | [Python](./algorithms/python/LongestTurbulentSubarray/maxTurbulenceSize.py)|Medium|
 |977|[Squares of a Sorted Array](https://leetcode.com/problems/squares-of-a-sorted-array/) | [Python](./algorithms/python/SquaresOfSortedArray/sortedSquares.py)|Easy|
 |976|[Largest Perimeter Triangle](https://leetcode.com/problems/largest-perimeter-triangle/) | [Python](./algorithms/python/LargestPerimeterTriangle/largestPerimeter.py)|Easy|
 |971|[Flip Binary Tree To Match Preorder Traversal](https://leetcode.com/problems/flip-binary-tree-to-match-preorder-traversal/) | [Python](./algorithms/python/FlipBinaryTreeToMatchPreorderTraversal/flipMatchVoyage.py)|Medium|
@@ -16,6 +17,7 @@ LeetCode
 |951|[Flip Equivalent Binary Trees](https://leetcode.com/problems/flip-equivalent-binary-trees/) | [Python](./algorithms/python/FlipEquivalentBinaryTrees/flipEquiv.py)|Medium|
 |950|[Reveal Cards In Increasing Order](https://leetcode.com/problems/reveal-cards-in-increasing-order/) | [Python](./algorithms/python/RevealCardsInIncreasingOrder/deckRevealedIncreasing.py)|Medium|
 |941|[Valid Mountain Array](https://leetcode.com/problems/valid-mountain-array/) | [Python](./algorithms/python/ValidMountainArray/validMountainArray.py)|Easy|
+|914|[X of a Kind in a Deck of Cards](https://leetcode.com/problems/x-of-a-kind-in-a-deck-of-cards/) | [Python](./algorithms/python/XOfAKindInADeckOfCards/hasGroupsSizeX.py)|Easy|
 |859|[Buddy Strings](https://leetcode.com/problems/buddy-strings/description/) | [C++](./algorithms/cpp/buddyStrings/BuddyStrings.cpp)|Easy|
 |858|[Mirror Reflection](https://leetcode.com/problems/mirror-reflection/description/) | [C++](./algorithms/cpp/mirrorReflection/MirrorReflection.cpp)|Medium|
 |852|[Peak Index in a Mountain Array](https://leetcode.com/problems/peak-index-in-a-mountain-array/description/) | [C++](./algorithms/cpp/peakIndexInAMountainArray/PeakIndexInAMountainArray.cpp)|Easy|
@@ -40,6 +42,7 @@ LeetCode
 |643|[Maximum Average Subarray I](https://leetcode.com/problems/maximum-average-subarray-i/description/) | [C++](./algorithms/cpp/maximumAverageSubarray/MaximumAverageSubarray.I.cpp), [Python](./algorithms/python/MaximumAverageSubarrayI/findMaxAverage.py)|Easy|
 |628|[Maximum Product of Three Numbers](https://leetcode.com/problems/maximum-product-of-three-numbers/) | [Python](./algorithms/python/MaximumProductOfThreeNumbers/maximumProduct.py)|Easy|
 |623|[Add One Row to Tree](https://leetcode.com/problems/add-one-row-to-tree/) | [Python](./algorithms/python/AddOneRowToTree/addOneRow.py)|Medium|
+|581|[Shortest Unsorted Continuous Subarray](https://leetcode.com/problems/shortest-unsorted-continuous-subarray/) | [Python](./algorithms/python/ShortestUnsortedContinuousSubarray/findUnsortedSubarray.py)|Easy|
 |572|[Subtree of Another Tree](https://leetcode.com/problems/subtree-of-another-tree/) | [Python](./algorithms/python/SubtreeOfAnotherTree/isSubtree.py)|Easy|
 |563|[Binary Tree Tilt](https://leetcode.com/problems/binary-tree-tilt/) | [Python](./algorithms/python/BinaryTreeTilt/findTilt.py)|Easy|
 |543|[Diameter of Binary Tree](https://leetcode.com/problems/diameter-of-binary-tree/) | [Python](./algorithms/python/DiameterOfBinaryTree/diameterOfBinaryTree.py)|Easy|
@@ -167,8 +170,8 @@ LeetCode
 |223|[Rectangle Area](https://leetcode.com/problems/rectangle-area/)| [C++](./algorithms/cpp/rectangleArea/RectangleArea.cpp)|Easy|
 |222|[Count Complete Tree Nodes](https://leetcode.com/problems/count-complete-tree-nodes/)| [C++](./algorithms/cpp/countCompleteTreeNodes/CountCompleteTreeNodes.cpp), [Python](./algorithms/python/CountCompleteTreeNodes/countNodes.py)|Medium|
 |221|[Maximal Square](https://leetcode.com/problems/maximal-square/)| [C++](./algorithms/cpp/maximalSquare/MaximalSquare.cpp)|Medium|
-|220|[Contains Duplicate III](https://leetcode.com/problems/contains-duplicate-iii/)| [C++](./algorithms/cpp/containsDuplicate/ContainsDuplicate.III.cpp)|Medium|
-|219|[Contains Duplicate II](https://leetcode.com/problems/contains-duplicate-ii/)| [C++](./algorithms/cpp/containsDuplicate/ContainsDuplicate.II.cpp)|Easy|
+|220|[Contains Duplicate III](https://leetcode.com/problems/contains-duplicate-iii/)| [C++](./algorithms/cpp/containsDuplicate/ContainsDuplicate.III.cpp), [Python](./algorithms/python/ContainsDuplicateIII/containsNearbyAlmostDuplicate.py)|Medium|
+|219|[Contains Duplicate II](https://leetcode.com/problems/contains-duplicate-ii/)| [C++](./algorithms/cpp/containsDuplicate/ContainsDuplicate.II.cpp), [Python](./algorithms/python/ContainsDuplicateII/containsNearbyDuplicate.py)|Easy|
 |218|[The Skyline Problem](https://leetcode.com/problems/the-skyline-problem/)| [C++](./algorithms/cpp/theSkylineProblem/TheSkylineProblem.cpp)|Hard|
 |217|[Contains Duplicate](https://leetcode.com/problems/contains-duplicate/)| [C++](./algorithms/cpp/containsDuplicate/ContainsDuplicate.cpp)|Easy|
 |216|[Combination Sum III](https://leetcode.com/problems/combination-sum-iii/)| [C++](./algorithms/cpp/combinationSum/combinationSum.III.cpp)|Medium|
@@ -293,7 +296,7 @@ LeetCode
 |81|[Search in Rotated Sorted Array II](https://oj.leetcode.com/problems/search-in-rotated-sorted-array-ii/)| [C++](./algorithms/cpp/searchInRotatedSortedArray/searchInRotatedSortedArray.II.cpp)|Medium|
 |80|[Remove Duplicates from Sorted Array II](https://oj.leetcode.com/problems/remove-duplicates-from-sorted-array-ii/)| [C++](./algorithms/cpp/removeDuplicatesFromSortedArray/removeDuplicatesFromSortedArray.II.cpp)|Medium|
 |79|[Word Search](https://oj.leetcode.com/problems/word-search/)| [C++](./algorithms/cpp/wordSearch/wordSearch.cpp)|Medium|
-|78|[Subsets](https://oj.leetcode.com/problems/subsets/)| [C++](./algorithms/cpp/subsets/subsets.cpp), [Java](./algorithms/java/src/subsets/subsets.java)|Medium|
+|78|[Subsets](https://oj.leetcode.com/problems/subsets/)| [C++](./algorithms/cpp/subsets/subsets.cpp), [Java](./algorithms/java/src/subsets/subsets.java), [Python](./algorithms/python/Subsets/subsets.py)|Medium|
 |77|[Combinations](https://oj.leetcode.com/problems/combinations/)| [C++](./algorithms/cpp/combinations/combinations.cpp)|Medium|
 |76|[Minimum Window Substring](https://oj.leetcode.com/problems/minimum-window-substring/)| [C++](./algorithms/cpp/minimumWindowSubstring/minimumWindowSubstring.cpp)|Hard|
 |75|[Sort Colors](https://oj.leetcode.com/problems/sort-colors/)| [C++](./algorithms/cpp/sortColors/sortColors.cpp)|Medium|

algorithms/python/ContainsDuplicateII/containsNearbyDuplicate.py

@@ -0,0 +1,21 @@
+# Method 1: using set
+
+def containsNearbyDuplicate(self, nums, k):
+    if len(nums) <= k + 1: return len(nums) != len(set(nums))
+    if k == 0: return False
+    s = set(nums[:k])
+    for i in range(k, len(nums)):
+        if nums[i] in s: return True
+        else:
+            s.remove(nums[i - k])
+            s.add(nums[i])
+    return False
+
+# Method 2: using dictionary
+def containsNearbyDuplicate(self, nums, k):
+    d = {}
+    for i, n in enumerate(nums):
+        if n in d and i - d[v] <= k:
+            return True
+        d[n] = i
+    return False

algorithms/python/ContainsDuplicateIII/containsNearbyAlmostDuplicate.py

@@ -0,0 +1,12 @@
+def containsNearbyAlmostDuplicate(self, nums, k, t):
+    if k < 1 or t < 0: return False
+    d = {}
+    w = t + 1
+    for i, n in enumerate(nums):
+        m = n // w
+        if m in d: return True
+        if m - 1 in d and abs(d[m-1] - n) <= t: return True
+        if m + 1 in d and abs(d[m+1] - n) <= t: return True
+        d[m] = n
+        if i >= k: del d[nums[i - k] // w]
+    return False

algorithms/python/LongestTurbulentSubarray/maxTurbulenceSize.py

@@ -0,0 +1,14 @@
+def maxTurbulenceSize(self, A):
+    res = inc = dec = 1
+    for i in range(1, len(A)):
+        if A[i] > A[i - 1]:
+            inc = dec + 1
+            dec = 1
+        elif A[i] < A[i - 1]:
+            dec = inc + 1
+            inc = 1
+        else:
+            inc = 1
+            dec = 1
+        res = max(res, max(inc, dec))
+    return res

algorithms/python/Subsets/subsets.py

@@ -0,0 +1,12 @@
+def subsets(self, nums):
+    res = []
+    def backtracking(temp, start):
+        res.append(temp[:])
+        for i in range(start, len(nums)):
+            temp.append(nums[i])
+            backtracking(temp, i + 1)
+            temp.pop()
+    
+    backtracking([], 0)
+    return res
+    

algorithms/python/XOfAKindInADeckOfCards/hasGroupsSizeX.py

@@ -0,0 +1,19 @@
+# Method 1: find the greatest common divisor using iteration
+
+def hasGroupsSizeX(self, deck):
+    if len(deck) < 2: return False
+    vals = collections.Counter(deck).values()
+    for n in range(2, max(vals) + 1):
+        if all(v % n == 0 for v in vals): return True
+    return False
+
+# Method 2: find the greatest common divisor using reduce
+# Time complexity: O(n)
+def hasGroupsSizeX(self, deck):
+    from functools import reduce
+    if len(deck) < 2: return False
+    vals = collections.Counter(deck).values()
+    def gcd(a, b):
+        while b: a, b = b, a % b
+        return a
+    return reduce(gcd, vals)