#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <stdbool.h>    // for bool

// Check if the doubles are equal with 'eps' approximation
bool sameDouble(double first, double second, double eps) {
    return fabs(first - second) < eps;
}

double f0(int value) {
    double x = (double)value + 12.28;
    double eps = 0.000001;

    // Check for bad parameter
    if (sameDouble(cos(x), 0.0000000000, eps)) {
        return -1;
    }

    return tan(x);
}

double f1(int value) {
    return (double)value - 7.92;
}

double f2(int value) {
    return sqrt(pow((double)value, 4) + 3.32);
}

int getUserInput(int *input, int INPUT_MIN, int INPUT_MAX) {
    int result = scanf_s("%d", input);
    if (result == 1 && *input >= INPUT_MIN && *input <= INPUT_MAX) {
        return 0;
    }

    return -1;
}

int main(int argc, char *argv[])
{
    // Constants
    const int ROWS = 2;
    const int MIN_K = 1;
    const int MAX_INT = 1000000;
    const char* errorMessage = "ERROR - USER INPUT\n";
    const int ERROR = -1;

    int K;

    printf_s("K = ");
    if (getUserInput(&K, MIN_K, MAX_INT) == -1) {
        printf_s(errorMessage);
        return ERROR;
    }

    // Allocate memory and make each R[i, j]
    int **R;
    R = (int**)malloc(ROWS * sizeof *R);
    for(int row = 0; row < ROWS; ++row) {
        R[row] = (int*)malloc(K * sizeof *R[row]);
        for(int col = 0; col < K; ++col) {

            printf_s("R[%d][%d] = ", row, col);

            // Provided bad input
            if (scanf_s("%d", &R[row][col]) != 1) {
                printf_s(errorMessage);

                // Free memory (error occured on row-th itteration)
                for (int f = 0; f < row; ++f) {
                    free(R[f]);
                }
                free(R);

                // Quit main with ERROR_CODE -1
                return ERROR;
            }
        }
    }

    // Allocate S array to store results
    double* S = (double*)malloc(sizeof(double) * K);

    // Create static array for functions pointers
    double (*functions[])(int) = { f0, f1, f2 };

    int value;
    int passValue;

    // Iterate over R to set elements of S
    for (int m = 0; m < K; ++m) {
        value = R[0][m];
        passValue = R[1][m];

        switch (value) {
        case 0:
            S[m] = functions[0](passValue);
            break;
        case 1:
            S[m] = functions[1](passValue);
            break;
        case 2:
            S[m] = functions[2](passValue);
            break;
        default:
            S[m] = R[1][m];
            break;
        }
    }

    // Print results to the user
    for (int i = 0; i < K; ++i) {
        printf_s("S[%d] = %f\n", i, S[i]);
    }

    // Free memory
    for(int i = 0; i < ROWS; ++i) {
        free(R[i]);
    }
    free(R);
    free(S);

    return 0;
}