poj2624

简单题

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#include <iostream>
#include <cstdlib>
#include <cstring>
#include <cstdio>
using namespace std;

struct Point
{
    double x, y;
} point[5];

void input()
{
    for (int i = 1; i < 4; i++)
        scanf("%lf%lf", &point[i].x, &point[i].y);
    if (point[1].x != point[2].x || point[1].y != point[2].y)
        swap(point[2], point[3]);
    if (point[1].x != point[2].x || point[1].y != point[2].y)
        swap(point[0], point[1]);
    if (point[1].x != point[2].x || point[1].y != point[2].y)
        swap(point[2], point[3]);
}

void work()
{
    Point p;
    p.x = (point[0].x + point[3].x) / 2 - point[1].x;
    p.y = (point[0].y + point[3].y) / 2 - point[1].y;
    printf("%.3f %.3f\n", point[1].x + p.x * 2, point[1].y + p.y * 2);
}

int main()
{
    //freopen("t.txt", "r", stdin);
    while (~scanf("%lf%lf", &point[0].x, &point[0].y))
    {
        input();
        work();
    }
    return 0;
}