using System;
using System.Diagnostics;
using static System.Console;

public static class swarm{

public static vector randomvec(vector a,vector b,Random rnd){
	var x=new vector(a.size);
	for(int i=0;i<a.size;i++)x[i]=a[i]+(b[i]-a[i])*rnd.NextDouble();
	return x;
	}

public static vector run
(Func<vector,double>f,vector a,vector b,int seconds=1,double w=0.723)
{
int dim=a.size, N=8*dim;
vector[] x=new vector[N], v=new vector[N], p=new vector[N];
var fp=new double[N];
var rnd=new Random();
var g=randomvec(a,b,rnd);
double fg=f(g);
for(int i=0;i<N;i++){
	x[i]=randomvec(a,b,rnd);
	p[i]=x[i].copy();
	fp[i]=f(p[i]);
	if(fp[i]<fg){g=p[i].copy();fg=fp[i];}
	v[i]=randomvec(a-b,b-a,rnd)/2;
	}
var start_time=DateTime.Now;
do{
	for(int i=0;i<N;i++){
		v[i]=w*v[i]
			+rnd.NextDouble()*(p[i]-x[i])
			+rnd.NextDouble()*(g-x[i]);
		x[i]+=v[i];
		var fxi=f(x[i]);
		if(fxi<fp[i]){fp[i]=fxi;p[i]=x[i].copy();}
		if(fxi<fg)   {fg=fxi;   g=x[i].copy();}
	}
}while((DateTime.Now-start_time).TotalSeconds < seconds);
return g;	
}

}//class