HDU2001计算两点间距离

直接AC

#include <iostream>
#include <cstdio>
#include <cmath>
using namespace std;
int main()
{
	double x1, y1, x2, y2;
	while(cin >> x1 >> y1 >> x2 >> y2)
	{
		double instance = sqrt((x1-x2)*(x1-x2) + (y1-y2)*(y1-y2));
		printf("%.2f\n", instance);
	}
	return 0;
}