Merge pull request #14 from joybanerjee08/master

Karatsuba in C++

Author: Bhrigu Kansra

multiplication/karatsuba.cpp

@@ -0,0 +1,27 @@
+#include <iostream>
+#include<string>
+#include <algorithm> 
+#include <cmath>
+using namespace std;
+
+int karatsuba(int x, int y){
+	if ((to_string(x).length()==1) || (to_string(y).length()==1)) {
+		return x*y;
+  }
+	else{
+		int n = max(to_string(x).length(),to_string(y).length());
+		int z = n / 2;
+		int a = x / (int)pow(10,z);
+		int b = x % (int)pow(10,z);
+		int c = y / (int)pow(10,z);
+		int d = y % (int)pow(10,z);
+		int ac = karatsuba(a,c);
+		int bd = karatsuba(b,d);
+		int adbc = karatsuba(a+b,c+d) - ac - bd;
+		return ac * pow(10,2*z) + (adbc * pow(10,z)) + bd;
+}
+}
+
+int main() {
+  cout << karatsuba (923,1723);
+}