[Sync Iteration] python/secret-handshake/3

solutions/python/secret-handshake/3/secret_handshake.py

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+"""
+Secret Handshake.
+
+Convert a number's binary representation (up to five bits) to a
+sequence of actions in the secret handshake.
+
+The sequence of actions is determined by inspecting the rightmost five
+binary digits (least-significant bit on the right):
+
+- 1 (..00001): "wink"
+- 2 (..00010): "double blink"
+- 4 (..00100): "close your eyes"
+- 8 (..01000): "jump"
+- 16(..10000): reverse the order of the operations selected above
+
+Only the presence of a bit matters; higher bits beyond the five listed
+are ignored. The reverse bit (16) inverses the final list of actions.
+"""
+
+ACTIONS: tuple[str, str, str, str] = ("wink", "double blink", "close your eyes", "jump")
+
+
+def commands(binary_str: str) -> list[str]:
+    """
+    Return the list of secret-handshake actions for the given binary string.
+
+    The input should be a binary string whose rightmost character is the
+    least-significant bit. Up to five bits are considered, mapping to the
+    actions defined by the classic Exercism "Secret Handshake" exercise.
+    If the fifth bit is set, the final list of actions is reversed.
+
+    :param binary_str: Binary string (e.g. "10101"). Rightmost char is LSB.
+    :returns: A list of action strings in the computed order.
+    """
+    results: list[str] = []
+    # Iterate from least- to most-significant bit by reversing the string.
+    for i, char in enumerate(binary_str[::-1]):
+        # Check if the corresponding bit position matches the expected "1".
+        if char == "1" and i < 4:
+            results.append(ACTIONS[i])
+        elif char == "1" and i == 4:
+            # Fifth bit indicates the final list should be reversed.
+            results = results[::-1]
+    return results