UVA 11817 (球面幾何)

這題主要知道如何把經緯度轉化為三維點坐標即可

代碼：

#include 
#include 
#include 
#include 
using namespace std;

const double PI = acos(-1.0);
int t;
double lat[2], lng[2];

//角度轉化為弧度
double torad(double deg) {
    return deg / 180 * PI;
}

struct Point3 {
    double x, y, z;
    Point3() {}
    Point3(double x, double y, double z) {
        this->x = x;
        this->y = y;
        this->z = z;
    }
};

const double R = 6371009;

Point3 get_coord(double R, double lat, double lng) {
    lat = torad(lat);
    lng = torad(lng);
    return Point3(R * cos(lat) * cos(lng), R * cos(lat) * sin(lng), R * sin(lat));
}

double dist(Point3 p, Point3 q) {
    double dx = p.x - q.x;
    double dy = p.y - q.y;
    double dz = p.z - q.z;
    return sqrt(dx * dx + dy * dy + dz * dz);
}

int main() {
    scanf("%d", &t);
    while (t--) {
        scanf("%lf%lf%lf%lf", &lat[0], &lng[0], &lat[1], &lng[1]);
        Point3 p[2];
        p[0] = get_coord(R, lat[0], lng[0]);
        p[1] = get_coord(R, lat[1], lng[1]);
        double d = dist(p[0], p[1]);
        printf("%.0f\n", 2 * asin(d / 2 / R) * R - d);
    }
    return 0;
}