eliminate is_paired

data_structures/stacks/balanced_parentheses.py

@@ -12,42 +12,25 @@ def balanced_parentheses(parentheses: str) -> bool:
     >>>
     """
     stack = Stack()
+    bracket_pairs = {"(": ")", "[": "]", "{": "}"}
     for bracket in parentheses:
         if bracket in ("(", "[", "{"):
             stack.push(bracket)
         elif bracket in (")", "]", "}"):
-            if stack.is_empty() or not is_paired(stack.pop(), bracket):
+            if stack.is_empty() or bracket_pairs[stack.pop()] != bracket:
                 return False
     return stack.is_empty()
 
 
-def is_paired(left_bracket: str, right_bracket: str) -> bool:
-    """
-    >>> brackets = {"(" : ")", "[" : "]", "{" : "}"}
-    >>> for left_bracket, right_bracket in brackets.items():
-    ...     assert is_paired(left_bracket, right_bracket)
-    >>> is_paired("(", "}")
-    False
-    >>> is_paired("(", "]")
-    False
-    """
-    return (
-        left_bracket == "(" and right_bracket == ")" or
-        left_bracket == "[" and right_bracket == "]" or
-        left_bracket == "{" and right_bracket == "}"
-    )
-
-
 if __name__ == "__main__":
     from doctest import testmod
 
     testmod()
-    
+
     examples = ["((()))", "((())", "(()))"]
     print("Balanced parentheses demonstration:\n")
     for example in examples:
         print(
-            example,
-            "is",
+            f"{example} is",
             "balanced" if balanced_parentheses(example) else "not balanced",
         )