View Code of Problem 106

#include <algorithm>
#include <cctype>
#include <cmath>
#include <cstdio>
#include <iostream>
#include <map>
#include <stack>
#include <string>
#include <vector>
using namespace std;

int main(void)
{
    double x0, y0, x1, y1, r;
    while (cin >> x0 >> y0 >> x1 >> y1 >> r)
    {
        double d = sqrt(pow(x1 - x0, 2) + pow(y1 - y0, 2));
        if (d == 0)
        {
            cout << "重合" << endl;
        }
        else if (d > 2 * r)
        {
            cout << "相离" << endl;
        }
        else if (d == 2 * r)
        {
            cout << "相切" << endl;
        }
        else
        {
            double sita = 2 * acos(d / (2 * r));
            double s = r * r * sita - r * r * sin(sita);
            printf("相交 %.2lf\n", s);
        }
    }
}