POJ2420 寻找费马点 模拟退火（不会）/三分套三分

所谓的三分套三分 ， 题意RT

#include<iostream>
#include<algorithm>
#include<fstream>
#include<string>
#include<cmath>
#include<cstring>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<stack>
#include<sstream>
#include<cstdio>
#define INF 0x3f3f3f3f
#define inf 0x7FFFFFFF
#define MOD 100
#define pii pair<int,int>
#define eps 1e-6
#define equals(a,b) (fabs(a-b)<eps)
#define bug puts("bug")
#define re  register
const int maxn = 1e6 + 5;
const double PI = acos(-1.0);
typedef  long long ll;
using namespace std;

struct Point {
    double x, y;
    Point(){}
    Point(double _x,double _y):x(_x),y(_y){}
};

Point p[105];
int n;

double get_sum(double xx,double yy) {
    double res = 0;
    for (int i = 0; i < n; i++)  res += sqrt((xx - p[i].x) * (xx - p[i].x) + (yy - p[i].y) * (yy - p[i].y));
    return res;
}

double three(double x) {
    double l = 0.0, r = 10000.0;
    for (int i = 0; i < 100; i++) {
        double mid = (l + r) / 2;
        double mmid = (mid + r) / 2;
        if (get_sum(x, mid) < get_sum(x, mmid)) r = mmid;
        else l = mid;
    }
    return get_sum(x, l);
}

int main() {
    while (~scanf("%d", &n)) {
        for (int i = 0; i < n; i++) scanf("%lf %lf", &p[i].x, &p[i].y);
        double l = 0.0, r = 10000.0;
        for (int i = 0; i < 100; i++) {
            double mid = (l + r) / 2;
            double mmid = (mid + r) / 2;
            if (three(mid) < three(mmid)) r = mmid;
            else l = mid;
        }
        printf("%.0f\n", three(l));
    }
    return 0;
}