Fix: Correct stdlib complexity documentation details

Co-Authored-By: Claude <noreply@anthropic.com>

Co-Authored-By: Codex <codex@openai.com>

Author: heikkitoivonen

docs/stdlib/concurrent_futures.md

@@ -12,7 +12,7 @@ The `concurrent.futures` module provides high-level interfaces for asynchronousl
 | `executor.submit(fn, *args)` | O(1) | O(1) | Submit task to queue |
 | `executor.map(fn, iterable)` | O(n) | O(n) | Submit all tasks, n = item count |
 | `Future.result()` | O(1) | O(r) | Get result, r = result size |
-| `as_completed(futures)` | O(n log n) | O(n) | Heap-based iteration; yields as each completes |
+| `as_completed(futures)` | O(n log n) | O(n) | Sorts futures by id for lock ordering, then event-based iteration |
 | `wait(futures)` | O(n) | O(n) | Wait for futures |
 | `Executor` creation | O(1) | O(1) | Base class init |
 | `Future` creation | O(1) | O(1) | Pending future |
@@ -185,9 +185,9 @@ executor = ThreadPoolExecutor(max_workers=4)
 # Submit all tasks: O(n)
 futures = [executor.submit(task, i) for i in range(100)]  # O(n)
 
-# Get futures as they complete: O(n log n) for sorting
-# (maintains heap of pending futures)
-for future in as_completed(futures):  # O(n log n) time
+# Get futures as they complete: O(n log n) overall
+# (initial lock-order sorting + event-based waiter)
+for future in as_completed(futures):  # O(n log n) total
     result = future.result()  # O(1) per future
     process(result)
 ```
@@ -293,7 +293,7 @@ def process_with_timeout(items, timeout=30):
         # Submit all: O(n)
         futures = {executor.submit(task, item): item for item in items}
 
-        # Wait with timeout: O(n)
+        # Wait with timeout: O(n log n) overall
         try:
             for future in as_completed(futures, timeout=timeout):  # O(n log n)
                 result = future.result()

docs/stdlib/gzip.md

@@ -153,10 +153,10 @@ import gzip
 data = b'x' * 1000000
 compressed = gzip.compress(data, compresslevel=1)  # Fastest
 
-# Compression level 6 (default): O(n)
+# Compression level 6 (balanced): O(n)
 compressed = gzip.compress(data, compresslevel=6)  # Balanced
 
-# Compression level 9 (best): O(n) but with higher constant factor
+# Compression level 9 (default, best): O(n) but with higher constant factor
 compressed = gzip.compress(data, compresslevel=9)  # Slowest, best ratio
 ```
 
@@ -291,7 +291,7 @@ with gzip.open('text.gz', 'rb') as f:  # 'b' = binary
 ```python
 import gzip
 
-# For streaming: use default (6)
+# For streaming: use default (9)
 # Already optimized for sequential compression
 
 # For one-shot:
@@ -303,7 +303,7 @@ compressed = gzip.compress(data, compresslevel=1)  # Fastest
 # Storage critical: level 9
 compressed = gzip.compress(data, compresslevel=9)  # Best ratio
 
-# Default: level 6 (good balance)
+# Default: level 9 (best compression)
 compressed = gzip.compress(data)
 ```
 

docs/stdlib/hashlib.md

@@ -37,7 +37,7 @@ import hashlib
 data = b"test"
 
 # MD5 - O(n)
-h1 = hashlib.md5(data)  # O(4) - deprecated
+h1 = hashlib.md5(data)  # O(4) - cryptographically broken
 
 # SHA1 - O(n)
 h2 = hashlib.sha1(data)  # O(4)

docs/stdlib/io.md

@@ -139,14 +139,12 @@ print(stream.tell())  # 6
 # Read from position - O(n)
 print(stream.read())  # "World"
 
-# Seek from end - O(1)
-stream.seek(-5, 2)  # 2 = os.SEEK_END
-print(stream.read())  # "World"
+# Seek to end - O(1)
+stream.seek(0, 2)  # 2 = os.SEEK_END (only offset=0 allowed for text streams)
+print(stream.tell())  # 11
 
-# Seek from current - O(1)
-stream.seek(0)
-stream.read(5)       # Read "Hello"
-stream.seek(1, 1)    # 1 = os.SEEK_CUR
+# Seek to absolute position - O(1)
+stream.seek(6)
 print(stream.read())  # "World"
 ```