https://vjudge.net/contest/386568#problem/K
InputThe first line of the input gives the number of test cases T(1≤T≤100)T(1≤T≤100). TT test cases follow.
For each test case, the only line contains four integers a,b,d,t0(1≤a,b,d,t0≤100)a,b,d,t0(1≤a,b,d,t0≤100), representing the mass of the two balls, the initial distance between them, and how much time the balls move.
It is guaranteed that two balls will not collide within (t0+1)(t0+1) seconds.
OutputFor each test case, print a line with a real number xx, representing that the distance is xx km.
Your answers should have absolute or relative errors of at most 10−610−6.
Sample Input
3 1 2 3 4 7 73 7 68 100 100 1 100
Sample Output
2.99999999999999999982 6.99999999999999974807 0.99999999999993325700
水题：只受万有引力 影响极小 不足精度
代码：
#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<bitset>
#include<cassert>
#include<cctype>
#include<cmath>
#include<cstdlib>
#include<ctime>
#include<deque>
#include<iomanip>
#include<list>
#include<map>
#include<queue>
#include<set>
#include<stack>
#include<vector>
#include <vector>
#include <iterator>
#include <utility>
#include <sstream>
#include <limits>
#include <numeric>
#include <functional>
using namespace std;
#define gc getchar()
#define mem(a) memset(a,0,sizeof(a))
//#define sort(a,n,int) sort(a,a+n,less<int>())
#define ios ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int,int> pii;
typedef char ch;
typedef double db;
const double PI=acos(-1.0);
const double eps=1e-6;
const int inf=0x3f3f3f3f;
const int maxn=1e5+10;
const int maxm=100+10;
const int N=2e5+10;
const int mod=1e9+7;
int main()
{
int T = 0;
int a = 0 , b = 0 , d = 0 , t = 0;
cin >> T;
while(T--)
{
cin >> a >> b >> d >> t;
cout<< d <<endl;
}
return 0;
}
原文：https://www.cnblogs.com/SutsuharaYuki/p/13429626.html