简介

就是模拟退火的物理过程，每次随机逼近乘上温度，以\(e^{\Delta/T}\)的概率接受答案，随机一个概率比较

然后就是调参+乱搞

题目

Bzoj3680：吊打xxx

代码

# include <bits/stdc++.h>

# define RG register

# define IL inline

# define Fill(a, b) memset(a, b, sizeof(a))

using namespace std;

typedef long long ll;

const int _(1005);

IL int Input(){

    RG int x = 0, z = 1; RG char c = getchar();

    for(; c < '0' || c > '9'; c = getchar()) z = c == '-' ? -1 : 1;

    for(; c >= '0' && c <= '9'; c = getchar()) x = (x << 1) + (x << 3) + (c ^ 48);

    return x * z;

}

const double EPS(1e-15);

const double dt(0.99);

double x[_], y[_], w[_], ans, ansx, ansy;

int n;

# define Sqr(x) ((x) * (x))

IL double Dis(RG double x1, RG double y1, RG double x2, RG double y2){

    return sqrt(Sqr(x1 - x2) + Sqr(y1 - y2));

}

IL double Sum(RG double x0, RG double y0){

    RG double ret = 0;

    for(RG int i = 1; i <= n; ++i) ret += Dis(x[i], y[i], x0, y0) * w[i];

    return ret;

}

IL double SA(RG double T){

    RG double x0 = ansx, y0 = ansy, cnt = 1e18;

    for(; T > EPS; T *= dt){

        RG double dx = rand() * 2 - RAND_MAX, dy = rand() * 2 - RAND_MAX;

        RG double xx = x0 + T * dx;

        RG double yy = y0 + T * dy;

        RG double ret = Sum(xx, yy);

        if(ret < ans) ans = ret, ansx = xx, ansy = yy;

        if(ret < cnt || exp((cnt - ret) / T) * RAND_MAX > rand()){

            cnt = ret;

            x0 = xx, y0 = yy;

        }

    }

}

int main(RG int argc, RG char* argv[]){

    n = Input();

    srand(n + 19260817); RG double x0 = 0, y0 = 0;

    for(RG int i = 1; i <= n; ++i) x[i] = Input(), y[i] = Input(), w[i] = Input();

    for(RG int i = 1; i <= n; ++i) x0 += x[i], y0 += y[i];

    x0 /= n; y0 /= n; ansx = x0; ansy = y0;

    ans = Sum(x0, y0);

	SA(100000);

    printf("%.3lf %.3lf\n", ansx, ansy);

    return 0;

}