#include <iostream>
#include <math.h>

using namespace std;

struct vector2d {
    float x1;
    float x2;
};

float f(vector2d v) {
    return (v.x1-4)*(v.x1-4) + 20 * (v.x2 - 100) * (v.x2 - 100);
}

float f(float x1, float x2) {
    return (x1-4)*(x1-4) + 20 * (x2 - 100) * (x2 - 100);
}

vector2d min (vector2d v1, vector2d v2, vector2d v3, vector2d v4, vector2d v5) {
    vector2d v = min(f(v1), f(v2))==f(v1)?v1:v2;
    v = min(f(v), f(v3))==f(v)?v:v3;
    v = min(f(v), f(v4))==f(v)?v:v4;
    v = min(f(v), f(v5))==f(v)?v:v5;
}

float getRandom()  {
    int sign = rand()%2==0?-1:1;
    return ((double) rand() / (RAND_MAX)) * sign;
}

vector2d getRandomVector (vector2d v, float step){
    vector2d result;
    result.x1 = step*getRandom() + v.x1;
    result.x2 = step*getRandom() + v.x2;
    return result;
}

int main() {
    vector2d v_p; v_p.x1 = 7; v_p.x2 = 95;
    vector2d v_n;
    float step = 1.0f;
    float eps = 0.0001;
    srand(time(0));
    int iterations = 0;
    while (true) {
        vector2d v1, v2, v3, v4, v5;
        v1 = getRandomVector(v_p, step);
        v2 = getRandomVector(v_p, step);
        v3 = getRandomVector(v_p, step);
        v4 = getRandomVector(v_p, step);
        v5 = getRandomVector(v_p, step);
        v_n = min(v1, v2, v3, v4, v5);

        if (f(v_n) >= f(v_p)) {
            if (fabs(f(v_n) - f(v_p)) <= eps && iterations > 0) {
                break;
            }
            step*=0.1;
        }

        v_p = v_n;

        iterations++;
    }
    cout << "x1 = " << v_n.x1 << " x2 = " << v_n.x2 << endl;
    cout << "f(x1, x2) = " << f(v_n) << endl;
    cout << "iterations: " << iterations << endl;
    cout << "step: " << step << endl;

    return 0;
}