[Sync Iteration] python/resistor-color-trio/1

solutions/python/resistor-color-trio/1/resistor_color_trio.py

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+"""
+Resistor Color Trio.
+
+In Resistor Color Duo you decoded the first two colors.
+For instance: orange-orange got the main value 33.
+The third color stands for how many zeros need to be added to the main value.
+The main value plus the zeros gives us a value in ohms. For the exercise it
+doesn't matter what ohms really are.
+"""
+
+# Mapping of resistor color names to their corresponding digit values.
+COLOR_VALUES: dict[str, int] = {
+    "black": 0,
+    "brown": 1,
+    "red": 2,
+    "orange": 3,
+    "yellow": 4,
+    "green": 5,
+    "blue": 6,
+    "violet": 7,
+    "grey": 8,
+    "white": 9,
+}
+
+
+def label(colors: list[str]) -> str:
+    """
+    Return a human-readable label for a 3-band resistor value.
+
+    The first two colors form the significant digits and the third color is the multiplier
+    (number of trailing zeros). The resulting value is scaled to the largest whole unit
+    among ohms, kiloohms, megaohms, or gigaohms.
+
+    :param colors: Three resistor color names in order [band1, band2, multiplier].
+                   band1 and band2 provide the significant digits; multiplier adds zeros.
+    :return: Formatted resistance value string using the largest whole unit
+             (e.g., '47 kiloohms', '680 ohms').
+    :raises KeyError: If a color name is not recognized.
+    :raises IndexError: If fewer than three colors are provided.
+    """
+    prefix: str = f"{COLOR_VALUES[colors[0]]}{COLOR_VALUES[colors[1]]}"
+    postfix: str = f"{'0' * COLOR_VALUES[colors[2]]}"
+    int_val: int = int(prefix + postfix)
+
+    # Scale to the largest whole unit
+    # (ohms, kiloohms, megaohms, gigaohms) for readability
+    if 1000 <= int_val < 1000000:
+        return f"{int_val // 1000} kiloohms"
+
+    if 1000000 <= int_val < 1000000000:
+        return f"{int_val // 1000000} megaohms"
+
+    if 1000000000 <= int_val:
+        return f"{int_val // 1000000000} gigaohms"
+
+    return f"{int_val} ohms"