Add Base62 encoding and decoding algorithm.

Author: frangelbarrera

ciphers/base62.py

@@ -0,0 +1,49 @@
+import string
+
+CHARSET = string.digits + string.ascii_lowercase + string.ascii_uppercase
+
+def base62_encode(num: int) -> str:
+    """
+    Encodes a positive integer into a base62 string.
+    >>> base62_encode(0)
+    '0'
+    >>> base62_encode(123)
+    '1z'
+    >>> base62_encode(1000000)
+    '4C92'
+    """
+    if num == 0:
+        return CHARSET[0]
+    
+    arr = []
+    base = len(CHARSET)
+    while num:
+        num, rem = divmod(num, base)
+        arr.append(CHARSET[rem])
+    arr.reverse()
+    return "".join(arr)
+
+def base62_decode(string_val: str) -> int:
+    """
+    Decodes a base62 string into a positive integer.
+    >>> base62_decode('0')
+    0
+    >>> base62_decode('1z')
+    123
+    >>> base62_decode('4C92')
+    1000000
+    """
+    base = len(CHARSET)
+    strlen = len(string_val)
+    num = 0
+    
+    idx = 0
+    for char in string_val:
+        power = strlen - (idx + 1)
+        num += CHARSET.index(char) * (base**power)
+        idx += 1
+    return num
+
+if __name__ == "__main__":
+    import doctest
+    doctest.testmod()