HDU 5826 physics

该问题和xi，di均无关，碰撞只会使得速度反向，大小不会变。因此只要计算速度。

#pragma comment(linker, "/STACK:1024000000,1024000000")
#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<stack>
#include<iostream>
using namespace std;
typedef long long LL;
const double pi=acos(-1.0),eps=1e-;
void File()
{
    freopen("D:\\in.txt","r",stdin);
    freopen("D:\\out.txt","w",stdout);
}
inline int read()
{
    char c = getchar(); while(!isdigit(c)) c = getchar(); int x = ;
    while(isdigit(c)) { x = x *  + c - ''; c = getchar();  }
    return x;
}

const int maxn=;
int T,n;
double C,v0[maxn];

int main()
{
    scanf("%d",&T); while(T--)
    {
        scanf("%d%lf",&n,&C);
        for(int i=;i<=n;i++)
        {
            scanf("%lf",&v0[i]);
            int xi,di; scanf("%d%d",&xi,&di);
        }
        sort(v0+,v0+n+);
        int q; scanf("%d",&q);
        for(int i=;i<=q;i++)
        {
            int t,k; scanf("%d%d",&t,&k);
            printf("%.3lf\n",sqrt(2.0*C*t+v0[k]*v0[k]));
        }
    }
    return ;
}