Create previous-permutation-with-one-swap.py

Author: kamyu104

Python/previous-permutation-with-one-swap.py

@@ -0,0 +1,21 @@
+# Time:  O(n)
+# Space: O(1)
+
+class Solution(object):
+    def prevPermOpt1(self, A):
+        """
+        :type A: List[int]
+        :rtype: List[int]
+        """
+        for left in reversed(xrange(len(A)-1)):
+            if A[left] > A[left+1]:
+                break
+        else:
+            return A
+        right = len(A)-1
+        while A[left] <= A[right]:
+            right -= 1
+        while A[right-1] == A[right]:
+            right -= 1
+        A[left], A[right] = A[right], A[left]
+        return A