rt 下为代码

#include<iostream>
#include<cmath>
#include<iomanip>
using namespace std;
double homo(double x1,double x2,double y1,double y2){
	return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
}
int main(){
	double x1,x2,x3,y1,y2,y3,sum=0;
	cin>>x1>>y1>>x2>>y2>>x3>>y3;
	sum=homo(x1,y1,x2,y2);
	sum+=homo(x1,y1,x3,y3);
	sum+=homo(x2,y2,x3,y3);
	cout<<fixed<<setprecision(2)<<sum;
}

我吐了 这破红题调一晚上了