dwzcalculator.c

#include<math.h>
#include<time.h>
#include<stdio.h>
#include<stdlib.h>

#define min(a,b) (a < b ? a : b)
/*#define nelem(x) (sizeof(x) / sizeof((x)[0]))*/

void usage(void)
{
    printf("usage: dwzcalculator DWZ INDEX YEAR_OF_BIRTH NO_OPPONENTS OPPONENTS_DWZ[] POINTS\n");
}

int get_J(age)
int age;
{
    int J;

    if(age <= 20)
        J = 5;
    else if (age <= 25)
        J = 10;
    else
        J = 15;

    return J;
}

int get_E(age, dwz, index, J, W, We)
int age;
int dwz;
int index;
int J;
double W;
double We;
{
    double a0, a = 1, B, E0;
    int E;

    if (age < 20){
        a0 = dwz / 2000.0;
        if (a0 < 0.5 || a0 > 1)
            a = a0;
    }
    
    E0 = pow(dwz / 1000.0, 4) + J;

    if (dwz < 1300 && (double) W <= We)
        B = exp((1300 - dwz) / 150) - 1;
    else
        B = 0;

    E = round(a * E0 + B);

    if (B == 0)
        E = min(E, min(30, 5*index));
    else
        E = min(E, 150);

    return E;
}

int get_age(year_of_birth)
int year_of_birth;
{
    int age, year;
    time_t now;
    struct tm *mt;

    if (time(&now) != (time_t)(-1)){
        mt = localtime(&now);
        year = mt->tm_year + 1900;
    } else {
        return 26;
    }
    
    age = year - year_of_birth;
   
    return age;
}

int calculate_dwz(dwz, index, year_of_birth, nopp, opponent_dwz, points)
int dwz;
int index;
int year_of_birth;
int nopp;
int* opponent_dwz;
double points;
{
    double W = points, We;
    double opponent_average = 0.0;
    int age, new_dwz, D, E, J;
    int n = nopp;
    int i;
    
    if (points == 0)
        exit(EXIT_FAILURE);

    for (i = 0; i < n; ++i)
        opponent_average += opponent_dwz[i];
    opponent_average /= n;

    D = dwz - opponent_average;
    We = n * (1 / (1 + pow(10.0, (double)(-D / 400.0))));

    age = get_age(year_of_birth);

    J = get_J(age);

    E = get_E(age, dwz, index, J, W, We);

    new_dwz = dwz + (800 / (E + n)) * (W - We);

    return new_dwz;
}

int main(argc, argv)
int argc;
char** argv;
{
    double points = -1.0;
    int dwz, index, year, nopp, *opp = NULL;
    int new_dwz, i;

    if(argc < 7){
        fprintf(stderr, "ERROR: not enough parameters!!!\n");
        usage();
        exit(EXIT_FAILURE);
    }

    dwz = atoi(argv[1]);
    index = atoi(argv[2]);
    year = atoi(argv[3]);
    nopp = atoi(argv[4]);

    if (nopp <= 0 || nopp > 10){
        fprintf(stderr, "ERROR: no possible number of opponents!!!\n");
        usage();
        exit(EXIT_FAILURE);
    }

    if (nopp + 6 != argc){
        fprintf(stderr, "ERROR: wrong number of arguments!!!\n");
        usage();
        exit(EXIT_FAILURE);
    }

    opp = (int *) calloc(nopp, sizeof(int));
    if (opp == NULL){
        fprintf(stderr, "ERROR: could not allocate enough memory!!!\n");
        exit(EXIT_FAILURE);
    }

    for (i = 0; i < nopp; ++i)
        opp[i] = atoi(argv[5+i]);
    
    points = atof(argv[argc-1]);

    new_dwz = calculate_dwz(dwz, index, year, nopp, opp, points);
    free(opp);

    printf("DWZ %d --> %d(%d)\n", dwz, new_dwz, new_dwz-dwz);

    return EXIT_SUCCESS;
}