--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/grok_interview/merge_sort.py	Mon Dec 15 19:55:17 2025 -0800
@@ -0,0 +1,48 @@
+from concurrent.futures import ProcessPoolExecutor
+import random
+from typing import List
+
+def merge_sort(lst: List[int]) -> List[int]:          # no executor parameter!
+    if len(lst) <= 1:
+        return lst
+    middle = len(lst) // 2
+    # These run in separate processes → no shared thread pool problem
+    left = merge_sort(lst[:middle])
+    right = merge_sort(lst[middle:])
+    return merge(left, right)
+
+def merge(left: List[int], right: List[int]) -> List[int]:
+    res = []
+    i = j = 0
+    while i < len(left) and j < len(right):
+        if left[i] <= right[j]:
+            res.append(left[i])
+            i += 1
+        else:
+            res.append(right[j])
+            j += 1
+    res.extend(left[i:])
+    res.extend(right[j:])
+    return res
+
+RANGE = 10_000
+cpu_num = 10
+def main():
+    data = [random.randint(0, 100) for _ in range(RANGE)]
+    sorted_data = []
+    ranges = [i for i in range(RANGE // cpu_num, RANGE, RANGE // 100)]
+    with ProcessPoolExecutor() as executor:
+        for pos_range in ranges:
+            sorted_data.append(executor.submit(merge_sort, data[:pos_range]).result())
+
+    while len(sorted_data) > 1:
+        new_sorted_data = []
+        for i in range(0, len(sorted_data), 2):
+            if 
+            res = merge(sorted_data[i], sorted_data[i+1])
+            new_sorted_data.append(res)
+
+    print(len(sorted_data))
+
+if __name__ == "__main__":      # important on Windows/macOS
+        main()