Swimming Balls

Swimming Balls
https://vjudge.net/contest/318752#problem/J
如果直接算，各种球的情况都不清楚，因为放一个球之后，水位的变化也会影响之前放入的球，不如，二分最终的水位高度，这样每个球的贡献就有了

#include <iostream>
#include <cstdio>
#include <queue>
#include <algorithm>
#include <cmath>
#include <cstring>
#define inf 2147483647
#define N 1000010
#define p(a) putchar(a)
#define For(i,a,b) for(int i=a;i<=b;++i)
//by war
//2019.8.16
using namespace std;
int T,n;
double L,x,y,mid,W,D,V,w[N],r[N],eps=1e-10,ans,pai=3.141592653589793;
void in(int &x){
    int y=1;char c=getchar();x=0;
    while(c<'0'||c>'9'){if(c=='-')y=-1;c=getchar();}
    while(c<='9'&&c>='0'){ x=(x<<1)+(x<<3)+c-'0';c=getchar();}
    x*=y;
}
void o(int x){
    if(x<0){p('-');x=-x;}
    if(x>9)o(x/10);
    p(x%10+'0');
}

double v(double r){
    return 4.0000000/3.00000000*pai*r*r*r;
}

double deal(double h,int i){
    return pai*(r[i]*r[i]*h-h*h*h/3.0);
}

double lj(double x,int i){
    if(x-r[i]>eps)
        return v(r[i])/2.0+deal(min(r[i],x-r[i]),i);
    return v(r[i])/2.0-deal(r[i]-x,i);
}

bool check(double x){
    double t=V;
    For(i,1,n){
        if(1.0000000-w[i]>eps)
            t+=min(v(r[i])*w[i],lj(x,i));
        else
            t+=lj(x,i);
    }
    if(t/W/L-x>eps)
        return 1;
    return 0;
}
signed main(){
    in(T);
    while(T--){
        in(n);
        cin>>W>>L>>D>>V;
        if(V<eps){
            puts("0.0000000000");
            continue;
        }
        For(i,1,n)
            cin>>r[i]>>w[i];
        x=0;y=D+eps;
        while(y-x>eps){
            mid=(x+y)/2.0;
            if(check(mid))
                x=mid;
            else
                y=mid;
        }
        printf("%.10f\n",mid);
    }
    return 0;
}