#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <time.h>
#include <string.h>

typedef struct point {
    double x;
    double y;
    int flag;
}POINT;

int n = 0;

double func(double x) {
    n++;
    return pow((x - 2), 2);

}

double calcDot(double (*func)(double), double L, double x1, double x2) {
    return 1 / (2 * L) * (L * (x1 + x2) + func(x1) - func(x2));
}

double lowGrade(double (*func)(double), double L, double x1, double x2) {
    return (func(x1) + func(x2)) / 2 - L / 2 * (x2 - x1);
}

double calcL(double a, double b) {
    if ((2 * (a - 2)) > (2 * (b - 2))) {
        return (2 * (a - 2));
    }
    else {
        return (2 * (b - 2));
    }
}



int main() {
    POINT arr[1000] = { 0 };

    double a = 0, b = 5, accuracy = 0.1, L = calcL(a, b);
    double y = calcDot(&func, L, a, b);
    arr[0] = { a, func(a), 0 };
    arr[1] = { y,func(y),1 };
    arr[2] = { b,func(b),0 };
    int f = 2;
    double upperLimit = fmin(arr[0].y, arr[2].y);
    double lowerLimit = lowGrade(&func, L, a, b);

    int t[5] = { 0 };

    while (upperLimit - lowerLimit > accuracy) {
        double min = upperLimit;
        int r = 0;
        for (int i = 0; i < f + 1; i++) {
            if ((arr[i].flag != 0) && (lowerLimit <= arr[i].y) && (arr[i].y < min)) {
                min = arr[i].y;
                r = i;
            }
        }
        upperLimit = fmin(upperLimit, func(arr[r].x));
        lowerLimit = min;

        arr[r].y = func(arr[r].x);
        arr[r].flag = 0;
        arr[f + 2] = { arr[f].x,arr[f].y,arr[f].flag };
        arr[r + 1] = { arr[r].x,arr[r].y,arr[r].flag };
        arr[r] = { calcDot(&func,L,arr[r-1].x,arr[r].x), lowGrade(&func, L, arr[r-1].x,arr[r].x), 1 };
        arr[r + 2] = { calcDot(&func,L,arr[r].x,arr[r + 1].x), lowGrade(&func, L, arr[r].x,arr[r + 1].x), 1 };
        f += 2;
        for (int j = 0; j <= f; j++) {
            printf("[x = %lf; y = %lf]\n", arr[j].x, arr[j].y);
        }
    }
    printf("\n\n[%.4lf;%.4lf]\n", arr[3].x, arr[2].x, n);
    printf("Ymin = [%.4lf;%.4lf]\nIteretion:%d", lowerLimit, upperLimit, n);
    return 0;
}