lightoj-1305 - Area of a Parallelogram(几何)

Posted 2020-07-22 FireCool

1305 - Area of a Parallelogram
PDF (English) Statistics Forum
Time Limit: 1 second(s) Memory Limit: 32 MB
A parallelogram is a quadrilateral with two pairs of parallel sides. See the picture below:

 

Fig: a parallelogram

Now you are given the co ordinates of A, B and C, you have to find the coordinates of D and the area of the parallelogram. The orientation of ABCD should be same as in the picture.

Input
Input starts with an integer T (≤ 1000), denoting the number of test cases.

Each case starts with a line containing six integers Ax, Ay, Bx, By, Cx, Cy where (Ax, Ay) denotes the coordinate of A, (Bx, By) denotes the coordinate of B and (Cx, Cy) denotes the coordinate of C. Value of any coordinate lies in the range [-1000, 1000]. And you can assume that A, B and C will not be collinear.

Output
For each case, print the case number and three integers where the first two should be the coordinate of D and the third one should be the area of the parallelogram.

Sample Input
Output for Sample Input
3
0 0 10 0 10 10
0 0 10 0 10 -20
-12 -10 21 21 1 40
Case 1: 0 10 100
Case 2: 0 -20 200
Case 3: -32 9 1247

 

#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;

int main(){
    
    int T,ax,ay,bx,by,cx,cy,dx,dy;
    scanf("%d",&T);
    for(int t=1;t<=T;t++){
        scanf("%d%d%d%d%d%d",&ax,&ay,&bx,&by,&cx,&cy);
        dx = cx-bx+ax,dy = cy-by+ay;
        int area = abs((cy-by)*(ax-bx)-(ay-by)*(cx-bx));
        printf("Case %d: %d %d %d\n",t,dx,dy,area);
        // 下面这种写法时记得要对abs()进行类型转换，不然WA 
        //printf("Case %d: %d %d %d\n",t,dx,dy,(int)abs((cy-by)*(ax-bx)-(ay-by)*(cx-bx)));
    }    
}