链接
https://www.acwing.com/problem/content/666/

思路
小学计算问题

#include <cstdio>

int main()
{
    double a, b, c;
    scanf("%lf%lf%lf", &a, &b, &c);

    if (a + b > c && a + c > b && b + c > a) printf("Perimetro = %.1lf\n", a + b + c);
    else printf("Area = %.1lf\n", (a + b) * c / 2);

    return 0;
}