Excess 3 code (TheAlgorithms#11001)

* added excess-3 code

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* updated with fixes

* updated with fixes

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* Update excess_3_code.py

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Christian Clauss <[email protected]>

Author: 3 people

Diff for: bit_manipulation/excess_3_code.py

@@ -0,0 +1,27 @@
+def excess_3_code(number: int) -> str:
+    """
+    Find excess-3 code of integer base 10.
+    Add 3 to all digits in a decimal number then convert to a binary-coded decimal.
+    https://en.wikipedia.org/wiki/Excess-3
+
+    >>> excess_3_code(0)
+    '0b0011'
+    >>> excess_3_code(3)
+    '0b0110'
+    >>> excess_3_code(2)
+    '0b0101'
+    >>> excess_3_code(20)
+    '0b01010011'
+    >>> excess_3_code(120)
+    '0b010001010011'
+    """
+    num = ""
+    for digit in str(max(0, number)):
+        num += str(bin(int(digit) + 3))[2:].zfill(4)
+    return "0b" + num
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()