diff --git a/rounds/1_histogram/solution.py b/rounds/1_histogram/solution.py
index dffbee5..a3220cb 100644
--- a/rounds/1_histogram/solution.py
+++ b/rounds/1_histogram/solution.py
@@ -1,14 +1,21 @@
-"""Your Round 1 solution — byte-pair histogram.
+"""Round 1 solution — byte-pair histogram."""
 
-**Edit this file.** It currently delegates to ``baseline.py`` so everything
-passes out of the box. Replace the body of ``compute_histogram`` with your
-own faster implementation.
-"""
+import numpy as np
 
 
 def compute_histogram(path: str) -> dict[bytes, int]:
-    """Frequency of every 2-byte bigram in the file at ``path``."""
-    # TODO: remove this delegation and write your own implementation here.
-    from .baseline import compute_histogram as _baseline
+    data = np.fromfile(path, dtype=np.uint8)
+    if len(data) < 2:
+        return {}
 
-    return _baseline(path)
+    bigrams = (data[:-1].astype(np.uint16) << 8) | data[1:]
+
+    counts = np.bincount(bigrams, minlength=65536)
+
+    valid_indices = np.nonzero(counts)[0]
+    valid_counts = counts[valid_indices]
+
+    return {
+        int(idx).to_bytes(2, 'big'): int(count) 
+        for idx, count in zip(valid_indices, valid_counts)
+    }
diff --git a/rounds/3_dna/solution.py b/rounds/3_dna/solution.py
index 8b917da..075a25d 100644
--- a/rounds/3_dna/solution.py
+++ b/rounds/3_dna/solution.py
@@ -1,17 +1,76 @@
-"""Your Round 3 solution — DNA sequence matcher.
+"""Fast Round 3 solution: DNA sequence matcher."""
 
-**Edit this file.** It currently delegates to ``baseline.py`` so everything
-passes out of the box. Replace the body of ``find_matches`` with your
-own faster implementation.
-"""
+from __future__ import annotations
 
-from .baseline import find_matches as _baseline
+import os
+from concurrent.futures import ThreadPoolExecutor
+
+import numpy as np
+
+_NEWLINE = b"\n"
 
 
 def find_matches(fasta_path: str, pattern: bytes) -> list[tuple[str, list[int]]]:
-    """Find every FASTA record whose sequence contains ``pattern``.
+    """Find every FASTA record whose sequence contains ``pattern``."""
+    if not pattern:
+        return []
+
+    pattern_len = len(pattern)
+    pattern_value = np.frombuffer(pattern, dtype=np.uint64)[0]
+
+    with open(fasta_path, "rb") as file:
+        data = file.read()
+
+    records = data.split(b">")[1:]
+    worker_count = os.cpu_count()
+
+    chunk_size = (len(records) + worker_count - 1) // worker_count
+    chunks = [
+        records[start : start + chunk_size]
+        for start in range(0, len(records), chunk_size)
+    ]
+    with ThreadPoolExecutor(max_workers=worker_count) as executor:
+        groups = executor.map(
+            _scan_records,
+            chunks,
+            [pattern_value] * len(chunks),
+            [pattern_len] * len(chunks),
+        )
+
+    return [match for group in groups for match in group]
+
+
+def _scan_records(
+    records: list[bytes],
+    pattern_value: np.uint64,
+    pattern_len: int,
+) -> list[tuple[str, list[int]]]:
+    matches: list[tuple[str, list[int]]] = []
+    for record in records:
+        match = _scan_record(record, pattern_value, pattern_len)
+        if match is not None:
+            matches.append(match)
+    return matches
+
+
+def _scan_record(
+    record: bytes,
+    pattern_value: np.uint64,
+    pattern_len: int,
+) -> tuple[str, list[int]] | None:
+    record_id, _, wrapped_sequence = record.partition(_NEWLINE)
+    sequence = wrapped_sequence.replace(_NEWLINE, b"")
+    sequence_len = len(sequence)
+    if sequence_len < pattern_len:
+        return None
 
-    Returns ``[(record_id, [positions...]), ...]`` in file order.
-    """
-    # TODO: remove this delegation and write your own implementation here.
-    return _baseline(fasta_path, pattern)
+    windows = np.ndarray(
+        shape=(sequence_len - pattern_len + 1,),
+        dtype=np.uint64,
+        buffer=sequence,
+        strides=(1,),
+    )
+    positions = np.nonzero(windows == pattern_value)[0]
+    if positions.size:
+        return record_id.decode("ascii"), positions.tolist()
+    return None