let's try this again shall we

problems 1->10 of LC150

189-rotate-array/soln.py

@@ -0,0 +1,22 @@
+def rotate(self, nums: list[int], k: int) -> None:
+    """
+    Do not return anything, modify nums in-place instead.
+    """
+    # O(n) space and time
+    # n = len(nums)
+    # k %= n
+    # nums[:] = nums[n-k:] + nums[:n-k]
+
+    # O(n) time, O(1) space
+    # reverse full - then reverse chunks
+    def partrev(arr, low, high):
+        while low < high:
+            arr[low], arr[high] = arr[high], arr[low]
+            low += 1
+            high -= 1
+
+    n = len(nums)
+    k %= n
+    partrev(nums, 0, n - 1)
+    partrev(nums, 0, k - 1)
+    partrev(nums, k, n - 1)