rotate array

Author: springuper

rotateArray.py

@@ -0,0 +1,24 @@
+# @param nums, a list of integer
+# @param k, num of steps
+# @return nothing, please modify the nums list in-place.
+def rotate(nums, k):
+    def reverse(arr, start, end):
+        while start < end:
+            arr[start], arr[end] = arr[end], arr[start]
+            start += 1
+            end -= 1
+    n = len(nums)
+    k = k % n
+    reverse(nums, 0, n - 1)
+    reverse(nums, 0, k - 1)
+    reverse(nums, k, n - 1)
+
+nums = [1, 2, 3, 4, 5, 6, 7]
+rotate(nums, 3)
+assert nums == [5, 6, 7, 1, 2, 3, 4]
+nums = [1, 2, 3]
+rotate(nums, 0)
+assert nums == [1, 2, 3]
+nums = [1, 2, 3]
+rotate(nums, 4)
+assert nums == [3, 1, 2]