Data commit

Task/Jacobi-symbol/Swift/jacobi-symbol.swift

@@ -0,0 +1,40 @@
+import Foundation
+
+func jacobi(a: Int, n: Int) -> Int {
+  var a = a % n
+  var n = n
+  var res = 1
+
+  while a != 0 {
+    while a & 1 == 0 {
+      a >>= 1
+
+      if n % 8 == 3 || n % 8 == 5 {
+        res = -res
+      }
+    }
+
+    (a, n) = (n, a)
+
+    if a % 4 == 3 && n % 4 == 3 {
+      res = -res
+    }
+
+    a %= n
+  }
+
+  return n == 1 ? res : 0
+}
+
+print("n/a  0  1  2  3  4  5  6  7  8  9")
+print("---------------------------------")
+
+for n in stride(from: 1, through: 17, by: 2) {
+  print(String(format: "%2d", n), terminator: "")
+
+  for a in 0..<10 {
+    print(String(format: " % d", jacobi(a: a, n: n)), terminator: "")
+  }
+
+  print()
+}