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Karatsuba in C++ #14

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Oct 1, 2018
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Karatsuba in C++ #14

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27 changes: 27 additions & 0 deletions multiplication/karatsuba.cpp
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Original file line number Diff line number Diff line change
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#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);
}