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/*
* SYNOPSIS:
*
* # g++ -o gcd-cpp gcd.cpp
* # ./gcd-cpp 11 22 33 121
* # 11
*
*
* To use GNU Multiple Precision Arithmetic Library:
*
* # g++ -DGMP gcd.cpp -lgmpxx -lgmp -o gcd-cpp-gmp
* # ./gcd-cpp-gmp 1234567890987654321 987654321234567
* # 63
*
*/
#include <cstdlib>
#include <iostream>
#include <sstream>
#include <vector>
#if __cplusplus >= 201703L
#include <execution>
#include <numeric>
#endif
#ifdef GMP
#include <gmpxx.h>
typedef mpz_class Number;
#else
typedef unsigned int Number;
#endif
using namespace std;
typedef vector<Number> Numbers;
Number gcd(Number a, Number b) {
Number c;
while (b != 0) {
c = b;
b = a % b;
a = c;
}
return a;
}
#if __cplusplus >= 201703L
class GCD {
public:
Number operator()(Number a, Number b) const { return gcd(a, b); };
} GCD;
Number gcd(const Numbers &ns) {
return reduce(execution::par, begin(ns), end(ns), Number(0), GCD);
}
#else
Number gcd(const Numbers &ns) {
Number r = 0;
for (Numbers::const_iterator n = ns.begin(); n != ns.end(); ++n)
r = gcd(*n, r);
return r;
}
#endif
int main(int argc, char *argv[]) {
if (argc > 1) {
Numbers ns(argc - 1);
for (int n = 1; n < argc; ++n) {
stringstream str;
str << argv[n];
str >> ns[n - 1];
/* NOTE:
* For GMP we can just assign: ns[n-1] = argv[n],
* and sstream is not needed.
*/
}
cout << gcd(ns) << endl;
}
return EXIT_SUCCESS;
}
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