Submission #16978

#	Time	Username	Problem	Language	Result	Execution time	Memory
16978		taehoon1018	초록색 삼각형 (YDX13_green)	C++98	0 / 1	0 ms	1084 KiB

C

#include <stdio.h>
 
double area(int x1, int y1, int x2, int y2, int x3, int y3)
{
    double res = (x1*y2 + x2*y3 + x3*y1 - x2*y1 - x3*y2 - x1*y3);
    if (res < 0)
        res = -res;
 
    return res;
}
int main(void)
{
    int x[2001] = { 0 };
    int y[2001] = { 0 };
    int N = 0,count = 0;
    double sum = 0;
 
    scanf("%d", &N);
    for (int i = 0; i < N; i++)
    {
        scanf("%d%d", &x[i], &y[i]);
    }
    if (N < 3)
    {
        printf("%.12f", 0);
        return 0;
    }
    for (int a = 0; a < N-2;a++)
    {
        for (int b = a+1; b < N - 1;b++)
        {
            for (int c = b+1; c < N;c++)
            {
                sum += area(x[a], y[a], x[b], y[b], x[c], y[c]);
                count++;
            }
        }
    }
    sum /= N;
    sum /= N - 1;
    sum /= N - 2;
    sum *= 3;
 
    printf("%.12f\n", sum);
 
    return 0;
}
 

• Subtask 1: 0 / 1