Merge pull request #609 from aniakubik/eulerTotient

added extended Euler totient function

Math/extendedEuclidian.cpp

@@ -0,0 +1,51 @@
+#include <iostream>
+#include <algorithm>
+
+using namespace std;
+
+/*
+    for numbers a, b returns x, y such as x * a + y * b = gcd(a,b)
+*/
+
+pair<int,int> extendedEuclidian(int a, int b) {
+	int a_old = a, b_old = b;
+	if(a < b) swap(a,b);
+
+	int x = 0, y = 1, old_x = 1, old_y = 0;
+
+	int quotient, residue;
+	while (b) {
+		quotient = a / b;
+		residue = a % b;
+
+		a = b;
+		b = residue;
+
+		int temp;
+
+		temp = x;
+		x = old_x - quotient * x;
+		old_x = temp;
+		
+
+		temp = y;
+		y = old_y - quotient * y;
+		old_y = temp;
+	}
+
+	if(b_old > a_old) swap(old_x, old_y);
+
+	return make_pair(old_x, old_y); 
+
+}
+
+int main() {
+
+	int a, b;
+	cin >> a >> b;
+	pair<int,int> result = extendedEuclidian(a, b);
+
+	cout<< result.first << " " << result.second;
+
+
+}