add Array/next-permutation.py (dev)

Author: yennanliu

README.md

@@ -87,8 +87,8 @@
 016 | [3 Sum Closest](https://leetcode.com/problems/3sum-closest/) | [Python](https://github.com/yennanliu/CS_basics/blob/master/leetcode_python/Array/3sum-closest.py) | _O(n^2)_   | _O(1)_  | Medium |`Two Pointers`, `basic`, `trick`| AGAIN**
 018| [4 Sum](https://leetcode.com/problems/4sum/) | [Python](https://github.com/yennanliu/CS_basics/blob/master/leetcode_python/Array/4sum.py)   | _O(n^3)_  | _O(1)_    | Medium  | `k sum`, `Two Pointers`, `trick`, `hard` | AGAIN (not start)
 026 | [Remove Duplicates from Sorted Array](https://leetcode.com/problems/remove-duplicates-from-sorted-array/)|  [Python](https://github.com/yennanliu/CS_basics/blob/master/leetcode_python/Array/remove-duplicates-from-sorted-array.py) | _O(n)_   | _O(1)_  | Easy   | `Two Pointers`, `basic`, `trick` |  AGAIN*
-027 | [Remove Element](https://leetcode.com/problems/remove-element/) |[Python](https://github.com/yennanliu/CS_basics/blob/master/leetcode_python/Array/remove-element.py) | _O(n)_  | _O(1)_ | Easy  |`basic`| AGAIN* 
-031 | [Next Permutation](https://leetcode.com/problems/next-permutation/)| [Python](./Python/next-permutation.py) | _O(n)_  | _O(1)_          | Medium   | Tricky | 
+027 | [Remove Element](https://leetcode.com/problems/remove-element/) | [Python](https://github.com/yennanliu/CS_basics/blob/master/leetcode_python/Array/remove-element.py) | _O(n)_  | _O(1)_ | Easy  |`basic`| AGAIN* 
+031 | [Next Permutation](https://leetcode.com/problems/next-permutation/)| [Python](https://github.com/yennanliu/CS_basics/blob/master/leetcode_python/Array/next-permutation.py) | _O(n)_ | _O(1)_ | Medium | `trick`, `hard` | AGAIN (not start*)
 048 | [Rotate Image](https://leetcode.com/problems/rotate-image/)   | [Python](./Python/rotate-image.py) | _O(n^2)_      | _O(1)_         | Medium         ||
 054 | [Spiral Matrix](https://leetcode.com/problems/spiral-matrix/) | [Python](./Python/spiral-matrix.py) | _O(m * n)_    | _O(1)_         | Medium         ||
 059 | [Spiral Matrix II](https://leetcode.com/problems/spiral-matrix-ii/) |  [Python](./Python/spiral-matrix-ii.py) | _O(n^2)_ | _O(1)_      | Medium         ||

leetcode_python/Array/next-permutation.py

@@ -0,0 +1,76 @@
+# V0 
+
+# V1 
+# http://bookshadow.com/weblog/2016/09/09/leetcode-next-permutation/
+class Solution(object):
+    def nextPermutation(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: void Do not return anything, modify nums in-place instead.
+        """
+        size = len(nums)
+        for x in range(size - 1, -1, -1):
+            if nums[x - 1] < nums[x]:
+                break
+        if x > 0:
+            for y in range(size - 1, -1, -1):
+                if nums[y] > nums[x - 1]:
+                    nums[x - 1], nums[y] = nums[y], nums[x - 1]
+                    break
+        for z in range((size - x) / 2):
+            nums[x + z], nums[size - z - 1] = nums[size - z - 1], nums[x + z]
+
+# V1'
+# https://blog.csdn.net/fuxuemingzhu/article/details/82113409
+class Solution(object):
+    def nextPermutation(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: void Do not return anything, modify nums in-place instead.
+        """
+        n = len(nums)
+        i = n - 1
+        while i > 0 and nums[i] <= nums[i - 1]:
+            i -= 1
+        self.reverse(nums, i, n - 1)
+        if i > 0:
+            for j in range(i, n):
+                if nums[j] > nums[i-1]:
+                    self.swap(nums, i-1, j)
+                    break
+        
+    def reverse(self, nums, i, j):
+        """
+        contains i and j.
+        """
+        for k in range(i, (i + j) / 2 + 1):
+            self.swap(nums, k, i + j - k)
+
+        
+    def swap(self, nums, i, j):
+        """
+        contains i and j.
+        """
+        nums[i], nums[j] = nums[j], nums[i]
+        
+# V2 
+# Time:  O(n)
+# Space: O(1)
+class Solution(object):
+    # @param {integer[]} nums
+    # @return {void} Do not return anything, modify nums in-place instead.
+    def nextPermutation(self, num):
+        k, l = -1, 0
+        for i in range(len(num) - 1):
+            if num[i] < num[i + 1]:
+                k = i
+
+        if k == -1:
+            num.reverse()
+            return
+
+        for i in range(k + 1, len(num)):
+            if num[i] > num[k]:
+                l = i
+        num[k], num[l] = num[l], num[k]
+        num[k + 1:] = num[:k:-1]