58 lines
1.4 KiB
C++
58 lines
1.4 KiB
C++
#include <iostream>
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#include <cstdio>
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#include <cstdlib>
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#include <cmath>
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#define Mod 1000000007
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#define eps 1e-8
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using namespace std;
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int dx[8] = {0,0,1,-1,1,-1,1,-1};
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int dy[8] = {1,-1,0,0,1,1,-1,-1};
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double a,b,c,d,e,f;
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double dis(double x,double y,double z)
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{
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return sqrt(x*x + y*y + z*z);
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}
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double calc(double x,double y)
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{
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double A = c;
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double B = d*y+e*x;
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double C = f*x*y + a*x*x + b*y*y - 1.0;
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double delta = B*B-4.0*A*C;
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if(delta < 0.0) return Mod+10.0;
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delta = sqrt(delta);
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double soz1 = (-B + delta)/(2.0*A);
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double soz2 = (-B - delta)/(2.0*A);
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if(dis(x,y,soz1) < dis(x,y,soz2))
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return soz1;
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return soz2;
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}
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double Simulated_Annealing()
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{
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double x = 0,y = 0,z = sqrt(1.0/c);
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double step = 1.0, rate = 0.99;
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while(step > eps)
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{
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for(int k=0;k<8;k++)
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{
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double kx = x + step*dx[k];
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double ky = y + step*dy[k];
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double kz = calc(kx,ky);
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if(kz >= Mod) continue;
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if(dis(kx,ky,kz) < dis(x,y,z))
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{
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x = kx,y = ky,z = kz;
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}
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}
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step *= rate;
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}
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return dis(x,y,z);
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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%lf",&a,&b,&c,&d,&e,&f)!=EOF)
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{
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printf("%.7f\n",Simulated_Annealing());
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}
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return 0;
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}
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