Go: package main

import (
	"fmt"
	"math"
)

func main() {
	var n int
	fmt.Scan(&n)
	for i := 0; i < n; i++ {
		var xa, ya, ra, xb, yb, rb float64
		fmt.Scan(&xa, &ya, &ra, &xb, &yb, &rb)
		// println(xa, ya, ra, xb, yb, rb)
		dis := math.Sqrt((xa-xb)*(xa-xb) + (ya-yb)*(ya-yb))
		if dis + ra < rb {
			fmt.Println(-2)
		} else if dis + rb < ra {
			fmt.Println(2)
		} else if dis > rb + ra {
			fmt.Println(0)
		} else {
			fmt.Println(1)
		}
	}
}

C++: #include <iostream>
#include <vector>
#include <cmath>

inline float distance(float xa, float ya, float xb, float yb){
	return std::sqrt((xa - xb)*(xa - xb) + (ya - yb)*(ya - yb));
}

inline int judge(std::vector<float> ve){
	float center_dis = distance(ve[0], ve[1], ve[3], ve[4]);
	float r_dis = ve[2] + ve[5];
	if(center_dis > r_dis){
		return 0;	
	}else{
		if(ve[2] > ve[5]){
			return center_dis + ve[5] <= ve[2] ? 2 : 1;
		}else{
			return center_dis + ve[2] <= ve[5] ? -2 : 1;
		}
	}
}

int main(void){
	int num;
	std::vector<float> ve(6);

	std::cin >> num;

	for(int i = 0; i < num; ++i){
		std::cin >> ve[0] >> ve[1] >> ve[2] >> ve[3] >> ve[4] >> ve[5];
		
		std::cout << judge(ve) << std::endl;
	}
	return 0;
}

C++: #include <iostream>
#include <cmath>

using namespace std;

int main()
{
    double xa, ya, ra, xb, yb, rb;
    double d;
    int num;

    cin >> num;
    for (int i = 0; i < num; i++) {
        cin >> xa >> ya >> ra >> xb >> yb >> rb;
        
        d = sqrt((xa - xb) * (xa - xb) + (ya - yb) * (ya - yb));

        if (d > ra + rb) 
            cout << 0 << endl;
        else if (d <= abs(ra - rb))
            cout << 2 << endl;
        else if (d <= abs(rb - ra))
            cout << -2 << endl;
        else if ((abs(ra - rb) < d) && (d < abs(ra + rb)))
            cout << 1 << endl;
    }

    return 0;
}

C++: #include <iostream>
#include <cmath>

int main(){
	int N;
	std::cin >> N;
	
	while(N--){
		double xa, ya, ra, xb, yb, rb;
		std::cin >> xa >> ya >> ra >> xb >> yb >> rb;
		double d = hypot((xa - xb), (ya - yb)); //distance
		
		if(d > ra + rb)
			std::cout << 0 << std::endl;
		else if(d < fabs(ra - rb))
			std::cout << (ra - rb ? 2 : -2) << std::endl;
		else
			std::cout << 1 << std::endl;
	}
    return 0;
}

C++: #include <iostream>
#include <stdio.h>
#include <vector>
#include <string>
#include <sstream>
#include <algorithm>
#include <complex>
#include <map>
using namespace std;
typedef long long ll;
typedef pair<int, int> PII;
typedef vector<int> VI;
typedef vector<VI> VVI;
#define rep(i,n) for (int i=0; i < (n); i++)

typedef double D;      // 座標値の型。doubleかlong doubleを想定
typedef complex<D> P;  // Point
typedef pair<P, P> L;  // Line
typedef vector<P> VP;
const D EPS = 1e-9;    // 許容誤差。問題によって変える
#define X real()
#define Y imag()
#define LE(n,m) ((n) < (m) + EPS)
#define GE(n,m) ((n) + EPS > (m))
#define EQ(n,m) (abs((n)-(m)) < EPS)

// 内積　dot(a,b) = |a||b|cosθ
D dot(P a, P b) {
  return (conj(a)*b).X;
}
// 外積　cross(a,b) = |a||b|sinθ
D cross(P a, P b) {
  return (conj(a)*b).Y;
}

// 2円の共通接線。返される各直線に含まれる頂点は円との接点となる
vector<L> tangentLines(P a, D ar, P b, D br) {
  vector<L> ls;
  D d = abs(b-a);
  rep (i,2) {
    D sin = (ar - (1-i*2)*br) / d;
    if (!LE(sin*sin, 1)) break;
    D cos = sqrt(max(1 - sin*sin, 0.0));
    rep (j,2) {
      P n = (b-a) * P(sin, (1-j*2)*cos) / d;
      ls.push_back(L(a + ar*n, b + (1-i*2)*br*n));
      if (cos < EPS) break;  // 重複する接線を無視（重複していいならこの行不要）
    }
  }
  return ls;
}

int main() {
  int n;
  cin >> n;
  D xa, ya, ra, xb, yb, rb;
  rep (_,n) {
    cin >> xa >> ya >> ra >> xb >> yb >> rb;

    vector<L> ls = tangentLines(P(xa,ya), ra, P(xb,yb), rb);
    if (ls.size() == 4) cout << 0;
    else if (ls.size() == 0) cout << ((ra < rb) ? -2 : 2);
    else cout << 1;
    cout << endl;
  }
  return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <vector>
#include <set>
#include <cmath>

using namespace std;

#define EPS (1e-10)
#define EQ(a,b) (abs((a) - (b)) < EPS)

int main(){
	int n;
	cin>>n;

	for(int i = 0; i < n; i++){
		double xa,ya,ra,xb,yb,rb;
		cin>>xa>>ya>>ra>>xb>>yb>>rb;
		double dist=(ya-yb)*(ya-yb)+(xa-xb)*(xa-xb);
		// AÆBªdÈçÈ¢
		if(!EQ((ra+rb)*(ra+rb),dist)&&(ra+rb)*(ra+rb)<dist)
			cout<<0<<endl;
		// ~üªðíé
		else if(EQ(abs(ra-rb)*abs(ra-rb),dist)||(abs(ra-rb))*(abs(ra-rb))<dist||EQ((ra+rb)*(ra+rb),dist))
			cout<<1<<endl;
		else
			// Ç¿ç©ªÉ¶Ý·é
			if(ra>rb)
				cout<<2<<endl;
			else
				cout<<-2<<endl;
	}

	return 0;
}

C++: #include<iostream>
#include<string>
#include<cstdio>
#include<algorithm>
#include<stack>
#include<queue>
#include<vector>
#include<cmath>
#include<utility>
#define ll long long int
#define ld long double
#define INF 1000000000
#define EPS 0.0000000001
#define rep(i,n) for(i=0;i<n;i++)
using namespace std;
typedef pair<int, int> P;

string str;

int main()
{
  ll n,i;
  ld xa,ya,ra,xb,yb,rb;
  ld dist;

  cin>>n;
  rep(i,n){

    cin>>xa>>ya>>ra>>xb>>yb>>rb;
    dist=sqrt( (xa-xb)*(xa-xb)+(ya-yb)*(ya-yb) );//2????????????????????¢

    ld lr=max(ra,rb);//?????????????????????
    ld sr=min(ra,rb);//?????????????????????

    if(dist>lr+sr)//AB?????¢??????????????¨???
      cout<<"0"<<endl;
    else{
      if(sr<dist || lr==sr || (dist<sr && dist+sr>lr))//?????????????????¢??????????????????????????§??????
	cout<<"1"<<endl;
      else if(rb<ra && dist<ra)
	cout<<"2"<<endl;
      else if(ra<rb && dist<rb)
	cout<<"-2"<<endl;
    }
  }
}

C++: #define _USE_MATH_DEFINES

#include <iostream>
#include <string>
#include <sstream>
#include <iomanip>
#include <cmath>
#include <algorithm>
#include <utility>
#include <vector>
#include <numeric>

using namespace std;

struct Circle
{
	double x, y;
	double r;
};

int hit(Circle c0, Circle c1)
{
	double x = (c1.x - c0.x);
	double y = (c1.y - c0.y);

	double d = sqrt(x * x + y * y);
	if (d <= c0.r + c1.r)
	{
		if (c0.r + d <= c1.r)
		{
			return -2;
		}
		else if (c1.r + d <= c0.r)
		{
			return 2;
		}
		else
		{
			return 1;
		}
	}
	else
	{
		return 0;
	}
}

int main()
{
	int n;
	for (cin >> n; n--;)
	{
		Circle c0, c1;
		cin >> c0.x >> c0.y >> c0.r;
		cin >> c1.x >> c1.y >> c1.r;

		cout << hit(c0, c1) << endl;
	}
}

C++: #include	<iostream>
#include	<cstdio>
#include	<cmath>

using namespace std;

int main(void) {
	int ds;
	cin >> ds;
	
	for(int i = 0; i < ds; i++) {
		double d, r1[3], r2[3];
		for(int j = 0; j < 3; j++)
			cin >> r1[j];
		for(int j = 0; j < 3; j++)
			cin >> r2[j];
		
		d = (r2[0] - r1[0]) * (r2[0] - r1[0]) + (r2[1] - r1[1]) * (r2[1] - r1[1]);
		
		if( d < abs(r1[2] - r2[2]) ) {
			cout << "2" << endl;
		}else if( d < abs(r2[2] - r1[2]) ) {
			cout << "-2" << endl;
		}else if( (abs(r1[2] - r2[2]) < d && d < r1[2] + r2[2]) || d == r1[2] + r2[2] ) {
			cout << "1" << endl;
		}else {
			cout << "0" << endl;
		}
	}
	return 0;
}