pku1940.cpp

这是ACM 方面的资料 是PKU的 北京大学的出来的

#include <stdio.h>

typedef struct 
{
	double x, y;
}Point;

Point p[100000];

int main()
{
	int i, N;
	double oddx, oddy, evenx, eveny, x, y;
	while (scanf("%d", &N) != -1)
	{
		for (i = 0; i < N; i++)
		{
			scanf("%lf %lf", &p[i].x, &p[i].y);
		}
		oddx = 0;
		oddy = 0;
		evenx = 0;
		eveny = 0;
		for (i = 0; i < N; i++)
		{
			if (i % 2 == 1)
			{
				oddx += p[i].x;
				oddy += p[i].y;
			}
			else
			{
				evenx += p[i].x;
				eveny += p[i].y;
			}
		}
		x = evenx - oddx;
		y = eveny - oddy;
		printf("%d ", N);
		printf("%lf %lf ", x, y);
		for (i = 0; i < N - 1; i++)
		{
			x = 2 * p[i].x - x;
			y = 2 * p[i].y - y;
			printf("%lf %lf ", x, y);
		}
		printf("\n");
	}
	return 0;
}