pythagorean.cpp

#include <iostream>
#include <boost/timer.hpp>
/*###########################################
 *入力された値がピタゴラス数かどうかを判定
###########################################*/
int main(){
	int z,z2;
	std::cout << "X^2 + Y^2 = Z^2" <<std::endl;
	std::cout << "Input Z?" << std::endl;
	std::cin >> z;
	if(z<1){
		std::cout << "An unexpected input has been detected." << std::endl;
		std::cout << "Please input an unsigned integer." << std::endl;
		return -1; //異常終了
	}

	z2 = z * z;
	int counter = 0;
	boost::timer t;
	for(int x = 1; x * x < z2 >> 1; x++){
		int x2 = x * x;
		for(int y = x; y * y <= z2 - x2; y++){
			int y2 = y * y;
			if(x2 + y2 == z2){
				std::cout << x << "^2 + " << y << "^2 = " << z << "^2" << std::endl;
				counter++;
			}
		}
	}
	std::cout << "Done. " << counter << "pattern(s) found.["
						<< t.elapsed() << "sec.]" << std::endl;
	return 0;
}