feat(day 53): add decimal-to_binary converter with reverse-build and optimized approach

Author: JohnSunny21

FreeCodeCamp/CodingQ/DecToBinary.py

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+"""
+Decimal to Binary
+Given a non-negative integer, return its binary representation as a string.
+
+A binary number uses only the digits 0 and 1 to represent any number. To convert a decimal number to binary, repeatedly divide the number by 2 and record the remainder. Repeat until the number is zero. Read the remainders last recorded to first. For example, to convert 12 to binary:
+
+12 ÷ 2 = 6 remainder 0
+6 ÷ 2 = 3 remainder 0
+3 ÷ 2 = 1 remainder 1
+1 ÷ 2 = 0 remainder 1
+12 in binary is 1100.
+
+"""
+
+
+def to_binary(decimal):
+    binary = ""
+    while decimal > 0:
+        remainder = decimal % 2
+        binary += str(remainder)
+        decimal = decimal // 2
+
+    return binary[::-1]
+
+
+def to_binary_(decimal):
+
+    if decimal == 0:
+        return '0'
+    
+    binary = ''
+    while decimal > 0:
+        remainder = decimal % 2
+        binary = str(remainder) + binary
+        decimal = decimal // 2
+
+    return binary
+
+if __name__ == "__main__":
+    print(to_binary(5))
+    print(to_binary(12))
+    print(to_binary(50))
+    print(to_binary(99))
+    print(to_binary(0))

FreeCodeCamp/CodingQ/DecToBinaryTest.py

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+import unittest
+from DecToBinary import to_binary
+
+class DecToBinaryTest(unittest.TestCase):
+
+    def test1(self):
+        self.assertEqual(to_binary(5),"101")
+
+    def test2(self):
+        self.assertEqual(to_binary(12),"1100")
+
+    def test3(self):
+        self.assertEqual(to_binary(50),"110010")
+
+    def test4(self):
+        self.assertEqual(to_binary(99),"1100011")
+
+    
+
+if __name__ == "__main__":
+    unittest.main()