HZNUOJ


Problem_ID: B
Result: Accepted
Time: 6ms
Memory: 1116kB
Author: 2018212212033
In contest: 1273

#include<stdio.h>
#include<math.h>
int main(){
	double a,b,c,p,s;
while(scanf("%lf%lf%lf",&a,&b,&c)!=-1){
	if(a<b+c&&b<a+c&&c<a+b){
		p=(a+b+c)/2;
		s=sqrt(p*(p-a)*(p-b)*(p-c));
	printf("%.2f\n",s);}
	else printf("invalid triangle\n");
}
}