【題目敘述】https://zerojudge.tw/ShowProblem?problemid=e512
【解題想法】
- 題目給定平行四邊形的「兩個相鄰邊」的端點的 (x, y)座標，這四個端點中必有兩個座標是同一點。
- 決定三個相異的座標點後，即可決定第四點的座標。
#include <iostream>
#include <iomanip>
using namespace std;
int main() {
double x[4], y[4];
double x1, y1, x2, y2, x3, y3;
while (cin >> x[0] >> y[0] >> x[1] >> y[1] >> x[2] >> y[2] >> x[3] >> y[3]){
if (x[1] == x[2] && y[1] == y[2]){
x1 = x[0]; y1 = y[0];
x2 = x[1]; y2 = y[1];
x3 = x[3]; y3 = y[3];
} else if (x[0] == x[2] && y[0] == y[2]){
x1 = x[1]; y1 = y[1];
x2 = x[0]; y2 = y[0];
x3 = x[3]; y3 = y[3];
} else if (x[0] == x[3] && y[0] == y[3]){
x1 = x[1]; y1 = y[1];
x2 = x[0]; y2 = y[0];
x3 = x[2]; y3 = y[2];
} else if (x[1] == x[3] && y[1] == y[3]){
x1 = x[0]; y1 = y[0];
x2 = x[1]; y2 = y[1];
x3 = x[2]; y3 = y[2];
}
cout << fixed << setprecision(3)
<< x3 + x1 - x2 << " " << y3 + y1 - y2 << "\n";
}
return 0;
}