57 lines
1.2 KiB
C++
57 lines
1.2 KiB
C++
#include <cstring>
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#include <iostream>
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#include <cstdio>
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#include <cmath>
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#include <algorithm>
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#include <queue>
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#include <map>
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#include <vector>
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using namespace std;
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#define eps (1e-9)
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double r,v,w,X,E;
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bool zero(double t)
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{
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return fabs(t)<eps;
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}
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double jifen(double t)
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{
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return (t*v*sqrt(r*r+t*t*v*v)+r*r*log(v*(t*v+sqrt(r*r+t*t*v*v))))/(2*v);
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}
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bool ok(double mid)
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{
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double tmp=X*sqrt(r*r*w*w+v*v)*(jifen(mid)-jifen(0));
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if(tmp+eps>E)
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return true;
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return false;
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}
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int main()
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{
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while(scanf("%lf%lf%lf%lf%lf",&r,&w,&v,&X,&E)!=EOF)
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{
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if(zero(r)&&zero(w)&&zero(v)&&zero(X)&&zero(E))
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break;
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double left=0,right=30*24*3600.0,ans=-1,mid;
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int cas=100;
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if(zero(r))
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{
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printf("%.4lf\n",sqrt(2*E/v/v));
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continue;
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}
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while(cas--)
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{
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mid=(left+right)/2;
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if(ok(mid))
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{
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ans=mid;
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right=mid;
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}
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else
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{
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left=mid;
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}
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}
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printf("%.4lf\n",ans);
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}
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return 0;
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}
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