asd

#include <iostream>
using namespace std;

struct vec {double x,y,z;};
class arr_vec {
private:
    double *x;
    double *y;
    double *z;
    int n;
public:
    arr_vec(int);
    ~arr_vec();
    void set(int,vec);
    vec operator[](int);
    friend arr_vec operator+(arr_vec,arr_vec);
    friend arr_vec operator*(arr_vec,double);
    friend arr_vec operator*(double,arr_vec);
};
vec operator+(vec a, vec b);
vec operator*(vec a, double b);

vec toVec(double x,double y, double z) {
    vec tmp;
    tmp.x=x;
    tmp.y=y;
    tmp.z=z;
    return tmp;
}

arr_vec::arr_vec(int N) {
    n=N;
    x=new double[n];
    y=new double[n];
    z=new double[n];
    for(int i=0;i<n;i++) {x[i]=i; y[i]=i+1; z[i]=i+2;} //по умолчанию.
}

arr_vec::~arr_vec() {
    delete[]x;
    delete[]y;
    delete[]z;
}

void arr_vec::set(int N, vec tmp) {
    if(n<N) return;
    x[N]=tmp.x;
    y[N]=tmp.y;
    z[N]=tmp.z;
}

vec arr_vec::operator [](int N) {
    return toVec(x[N],y[N],z[N]);
}

arr_vec operator+(arr_vec a,arr_vec b) {
    arr_vec c(a.n);
    for(int i=0; i<c.n; i++)
        c.set(i,a[i]+b[i]);
    return c;
}

vec operator+(vec a, vec b) {
    return toVec(a.x+b.x,a.y+b.y,a.z+b.z);
}

vec operator*(vec a, double b) {
    return toVec(a.x*b,a.y*b,a.z*b);
}

arr_vec operator*(arr_vec a,double k) {
    arr_vec c(a.n);
    for(int i=0; i<c.n; i++) {
        c.set(i,a[i]*k);
    }
    return c;
}

arr_vec operator*(double k, arr_vec a) {
    return a*k;
}