Data commit

Task/Jacobi-symbol/Python/jacobi-symbol.py

@@ -0,0 +1,21 @@
+def jacobi(a, n):
+    if n <= 0:
+        raise ValueError("'n' must be a positive integer.")
+    if n % 2 == 0:
+        raise ValueError("'n' must be odd.")
+    a %= n
+    result = 1
+    while a != 0:
+        while a % 2 == 0:
+            a /= 2
+            n_mod_8 = n % 8
+            if n_mod_8 in (3, 5):
+                result = -result
+        a, n = n, a
+        if a % 4 == 3 and n % 4 == 3:
+            result = -result
+        a %= n
+    if n == 1:
+        return result
+    else:
+        return 0