Added binary exponentiaion with respect to modulo (#1428)

* Added binary exponentiaion with respect to modulo

* Added miller rabin: the probabilistic primality test for large numbers

* Removed unused import

* Added test for miller_rabin

* Add test to binary_exp_mod

* Removed test parameter to make Travis CI happy

* unittest.main()  # doctest: +ELLIPSIS   ...

* Update binary_exp_mod.py

* Update binary_exp_mod.py

* Update miller_rabin.py

* from .prime_check import prime_check

Co-authored-by: Christian Clauss <cclauss@me.com>

maths/binary_exp_mod.py

@@ -0,0 +1,28 @@
+def bin_exp_mod(a, n, b):
+    """
+    >>> bin_exp_mod(3, 4, 5)
+    1
+    >>> bin_exp_mod(7, 13, 10)
+    7
+    """
+    # mod b
+    assert not (b == 0), "This cannot accept modulo that is == 0"
+    if n == 0:
+        return 1
+
+    if n % 2 == 1:
+        return (bin_exp_mod(a, n - 1, b) * a) % b
+
+    r = bin_exp_mod(a, n / 2, b)
+    return (r * r) % b
+
+
+if __name__ == "__main__":
+    try:
+        BASE = int(input("Enter Base : ").strip())
+        POWER = int(input("Enter Power : ").strip())
+        MODULO = int(input("Enter Modulo : ").strip())
+    except ValueError:
+        print("Invalid literal for integer")
+
+    print(bin_exp_mod(BASE, POWER, MODULO))