Task 10 exercise a

Uebung-03/find.py

@@ -0,0 +1,59 @@
+import math
+import random
+from multiprocessing import Pool
+from typing import Optional, Iterable, Tuple
+
+def gen_nums(n: int) -> list[int]:
+    assert n > 0
+    nums = list(range(2 ** n))
+    random.shuffle(nums)
+    return nums
+
+def chunks(n: int, p: int) -> Iterable[Tuple[int, int]]:
+    base, rem = divmod(n, p)
+    start = 0
+    for i in range(p):
+        size = base + (1 if i < rem else 0)
+        end = start + size
+        yield start, end
+        start = end
+
+def t_find(args: Tuple[int, int, list[int], int]) -> Optional[int]:
+    s, e, haystack, needle = args
+    for i in range(s, e):
+        if haystack[i] == needle:
+            return i
+    return None
+
+def find(needle: int, haystack: list[int]) -> Optional[int]:
+    size = len(haystack)
+    assert size >= 1
+
+    procs = int(math.log2(size))
+    ranges = list(chunks(size, procs))
+    with Pool(processes=procs) as pool:
+        res = pool.map(t_find, [(s, e, haystack, needle) for (s, e) in ranges])
+
+    for idx in res:
+        if idx is not None:
+            return idx
+    return None
+
+def fuzz_test(trials: int = 200, max_n: int = 16, seed: Optional[int] = None) -> None:
+    if seed is not None:
+        random.seed(seed)
+
+    for t in range(1, trials + 1):
+        n = random.randint(1, max_n)
+        arr = gen_nums(n)
+
+        idx_true = random.randrange(len(arr))
+        needle = arr[idx_true]
+        expected = idx_true
+
+        got = find(needle, arr)
+        assert got == expected, f"[t={t}] Expected {expected}, got {got}; n={n}"
+
+    print(f"Fuzz OK: {trials} trials, max_n={max_n}")
+
+fuzz_test(trials=1000, max_n=16)