[Sync Iteration] python/all-your-base/3

Author: exercism-solutions-syncer[bot]

solutions/python/all-your-base/3/all_your_base.py

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+"""
+Convert a sequence of digits in one base, representing a number,
+into a sequence of digits in another base, representing the same number.
+"""
+
+
+def rebase(input_base: int, digits: list[int], output_base: int) -> list[int]:
+    """
+    Convert a non-negative integer represented as digits in one base
+    to digits in another base.
+
+    :param int input_base: Base of the input digits; must be >= 2.
+    :param list[int] digits: Sequence of digits where each d satisfies
+                             0 <= d < input_base. Leading zeros are allowed;
+                             an empty list denotes 0.
+    :param int output_base: Base for the output digits; must be >= 2.
+    :returns: Digits of the same number in ``output_base``, without leading
+              zeros (except ``[0]`` for zero).
+    :rtype: list[int]
+    :raises ValueError: If ``input_base < 2``, if any digit violates
+                        ``0 <= d < input_base``, or if ``output_base < 2``.
+    """
+    # Step 1: Validate the Inputs (Before Any Calculations)
+    # Validate input_base >= 2
+    if input_base < 2:
+        raise ValueError("input base must be >= 2")
+
+    # Validate each digit is 0 <= d < input_base
+    for d in digits:
+        if not 0 <= d < input_base:
+            raise ValueError("all digits must satisfy 0 <= d < input base")
+
+    # Validate output_base >= 2
+    if output_base < 2:
+        raise ValueError("output base must be >= 2")
+
+    # Step 2: Calculate the Intermediate Value Using input_base and digits
+    # Start from the least significant number (from the right in original list)
+    # -> hence reverse the list
+    intermediate_val: int = sum(
+        digit * (input_base**i) for i, digit in enumerate(digits[::-1])
+    )
+
+    # Step 3: Convert the Intermediate Value to digits in output_base
+    answer: list[int] = []
+    while True:
+        # Compute quotient (new intermediate_val)
+        # and remainder (least significant digit)
+        intermediate_val, remainder = (
+            intermediate_val // output_base,
+            intermediate_val % output_base,
+        )
+        # Add the next least significant number into a new list of digits
+        # Start always from the right
+        answer.insert(0, remainder)
+        # Break the loop since reach zero, no more calculation needed
+        if intermediate_val == 0:
+            break
+
+    return answer