refactor(ciphers): improve variable naming for clarity in columnar transposition cipher

Author: Saiprashanth Pulisetti

ciphers/columnar_transposition.py

@@ -40,7 +40,7 @@ def _normalize_key(key: str) -> str:
 def _column_order(key: str) -> list[int]:
     # Stable sort by character then original index to handle duplicates
     indexed = list(enumerate(key))
-    return [i for i, _ in sorted(indexed, key=lambda t: (t[1], t[0]))]
+    return [i for i, _ in sorted(indexed, key=lambda indexed_pair: (indexed_pair[1], indexed_pair[0]))]
 
 
 def encrypt(plaintext: str, key: str) -> str:
@@ -85,9 +85,9 @@ def decrypt(ciphertext: str, key: str) -> str:
         return ciphertext
 
     order = _column_order(k)
-    L = len(ciphertext)
-    rows = (L + cols - 1) // cols
-    r = L % cols
+    text_len = len(ciphertext)
+    rows = (text_len + cols - 1) // cols
+    r = text_len % cols
 
     # Column lengths based on ragged last row (no padding during encryption)
     col_lengths: list[int] = []