UVA 10250 The Other Two Trees

题目

另两棵树

分析

给正方形对角两点坐标，求另两点坐标。应该是对0前面的正负号要求不高。

代码

#include <stdio.h>int main(void){    double x1, x2, ax1, ax2;    double y1, y2, ay1, ay2;    double a, b;    while (scanf("%lf%lf%lf%lf", &x1, &y1, &x2, &y2) != EOF) {        if (x1 == x2 && y1 == y2) {            printf("Impossible.\n");            continue;        }        /*        a + b = y1 - y2;        a - b = x2 - x1;        */        a = ((y1-y2)+(x2-x1))/2;        b = ((y1-y2)-(x2-x1))/2;        ax1 = x2 - a;        ay1 = y2 + b;        ax2 = x2 + b;        ay2 = y2 + a;        printf("%.10lf %.10lf %.10lf %.10lf\n", ax1, ay1, ax2, ay2);    }    return 0;}