如题

#include<bits/stdc++.h>
using namespace std;
int x[50001],y[50001],z[50001];
double distance(int x1,int y1,int z1,int x2,int y2,int z2){
	return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2)+(z1-z2)*(z1-z2));
}
int main(){
	int sl,hh;
	double jl;
	cin>>sl;
	for(int i=0;i<sl;i++){
		cin>>x[i]>>y[i]>>z[i];
	}
	sort(x,x+sl);
	sort(y,y+sl);
	sort(z,z+sl);
	jl=0;
	for(int i=0;i+1<sl;i++){
		jl+=distance(x[i],y[i],z[i],x[i+1],y[i+1],z[i+1]);
	}
	printf("%.3lf",jl);
	return 0;
}