HDU 2105 The Center of Gravity

http://acm.hdu.edu.cn/showproblem.php?pid=2105

Problem Description

Everyone know the story that how Newton discovered the Universal Gravitation. One day, Newton walked 
leisurely, suddenly, an apple hit his head. Then Newton discovered the Universal Gravitation.From then
on,people have sovled many problems by the the theory of the Universal Gravitation. What's more, wo also
have known every object has its Center of Gravity.
Now,you have been given the coordinates of three points of a triangle. Can you calculate the center 
of gravity of the triangle?

 

Input

The first line is an integer n,which is the number of test cases.
Then n lines follow. Each line has 6 numbers x1,y1,x2,y2,x3,y3,which are the coordinates of three points.
The input is terminated by n = 0.

 

Output

For each case, print the coordinate, accurate up to 1 decimal places.

 

Sample Input

2

1.0 2.0 3.0 4.0 5.0 2.0

1.0 1.0 4.0 1.0 1.0 5.0

0

 

Sample Output

3.0 2.7

2.0 2.3

代码：

#include <bits/stdc++.h>
using namespace std;

int main() {
    int n;
    while(~scanf("%d", &n)) {
        if(n == 0) break;
        for(int i = 1; i <= n; i ++) {
            double x1, y1, x2, y2, x3, y3;
            cin>> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
            double x = 0, y = 0;
            x = 1.0 * (x1 + x2 + x3) / 3;
            y = 1.0 * (y1 + y2 + y3) / 3;
            printf("%.1lf %.1lf\n", x, y);
        }
    }
    return 0;
}