标签：style   http   color   os   io   for   ar   cti   

UVA 10228 - Star not a Tree?

题目链接

题意：给定一些点，费马点(到这些点距离和最短)，输出距离和

思路：模拟退火去搞，初始温度1W步，降温系数设为0.83，然后每次找周围4个方向，做10次保证答案准确

代码：

#include <cstdio>
#include <cstring>
#include <cmath>
#include <ctime>
#include <cstdlib>
#include <algorithm>
using namespace std;

const int d[4][2] = {{1, 0}, {0, 1}, {-1, 0}, {0, -1}};

const int N = 105;
const double eps = 1e-3;

int t, n;

struct Point {
    double x, y, d;
    Point() {}
    Point(double a, double b) {
	x = a; y = b;
    }
} p[N];

double getdis(Point P) {
    double ans = 0;
    for (int i = 0; i < n; i++) {
	double dx = p[i].x - P.x;
	double dy = p[i].y - P.y;
	ans += sqrt(dx * dx + dy * dy);
    }
    return ans;
}

double gao() {
    int cnt = 10;
    double ans = 1e20, r = 0.83;
    srand(time(NULL));
    while (cnt--) {
	double step = 1e4;
	Point now = Point(rand() % 10001, rand() % 10001);
	now.d = getdis(now);
	while (step > eps) {
	    Point next;
	    for (int i = 0; i < 4; i++) {
		next = Point(now.x + step * d[i][0], now.y + step * d[i][1]);
		next.d = getdis(next);
		if (next.d < now.d)
		    now = next;
	    }
	    step *= r;
	    ans = min(ans, now.d);
	}
    }
    return ans;
}

int main() {
    scanf("%d", &t);
    while (t--) {
	scanf("%d", &n);
	for (int i = 0; i < n; i++)
	    scanf("%lf %lf", &p[i].x, &p[i].y);
	printf("%.0lf\n", gao());
	if (t) printf("\n");
    }
    return 0;
}

UVA 10228 - Star not a Tree?(模拟退火),布布扣,bubuko.com

UVA 10228 - Star not a Tree?(模拟退火)

标签：style   http   color   os   io   for   ar   cti   

原文地址：http://blog.csdn.net/accelerator_/article/details/38497533