Data commit

Task/Modular-inverse/NewLISP/modular-inverse.l

@@ -0,0 +1,30 @@
+(define (modular-multiplicative-inverse a n)
+    (if (< n 0)
+        (setf n (abs n)))
+
+    (if (< a 0)
+        (setf a (- n (% (- 0 a) n))))
+
+    (setf t 0)
+    (setf nt 1)
+    (setf r n)
+    (setf nr (mod a n))
+
+    (while (not (zero? nr))
+        (setf q (int (div r nr)))
+        (setf tmp nt)
+        (setf nt (sub t (mul q nt)))
+        (setf t tmp)
+        (setf tmp nr)
+        (setf nr (sub r (mul q nr)))
+        (setf r tmp))
+
+    (if (> r 1)
+        (setf retvalue nil))
+
+    (if (< t 0)
+        (setf retvalue (add t n))
+        (setf retvalue t))
+    retvalue)
+
+(println (modular-multiplicative-inverse 42 2017))