@@ -1,6 +1,5 @@
 """Round 1 solution — byte-pair histogram."""
 
-
 import numpy as np
 
 
@@ -9,8 +8,14 @@ def compute_histogram(path: str) -> dict[bytes, int]:
     if len(data) < 2:
         return {}
 
-    bigrams_16 = (data[:-1].astype(np.uint16) << 8) | data[1:]
-    
-    values, counts = np.unique(bigrams_16, return_counts=True)
-    
-    return {int(v).to_bytes(2, 'big'): int(c) for v, c in zip(values, counts)}
+    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)
+    }