#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>
#include <time.h>

typedef struct {
    int *arr, idx, n;
    pthread_mutex_t *m;
    pthread_barrier_t *b;
} data;

void *f(void *arg) {
    data d = *((data*) arg);
    d.arr[d.idx] = random() % 11 + 10;
    printf("T[%d] -> %d\n", d.idx, d.arr[d.idx]);
    pthread_barrier_wait(d.b);
    int i, stop;
    while(1) {
        stop = -1;
        pthread_mutex_lock(d.m);
        if(d.arr[d.idx] <= 0)
            break;
        stop = 1;
        for(i = 0; i < d.n; i++) {
            if(i != d.idx) {
                d.arr[i]--;
                if(d.arr[i] > 0)
                    stop = 0;
            }
        }
        if(stop == 1)
            break;
        pthread_mutex_unlock(d.m);
        // this is here only to produce more contention between threads
        usleep(100);
    }
    if(stop == -1)
        printf("Thread %d has been eliminated!\n", d.idx);
    else
        printf("Thread %d has won!\n", d.idx);
    pthread_mutex_unlock(d.m);
    return NULL;
}

int main(int argc, char *argv[]) {
    int n;
    printf("n = ");
    scanf("%d", &n);
    srandom(time(NULL));
    int i;
    int *arr = malloc(sizeof(int) * n);
    data *args = malloc(sizeof(data) * n);
    pthread_mutex_t *m = malloc(sizeof(pthread_mutex_t));
    pthread_mutex_init(m, NULL);
    pthread_barrier_t *b = malloc(sizeof(pthread_barrier_t));
    pthread_barrier_init(b, NULL, n);
    pthread_t *th = malloc(sizeof(pthread_t) * n);
    for(i = 0; i < n; i++) {
        args[i].m = m;
        args[i].b = b;
        args[i].arr = arr;
        args[i].n = n;
        args[i].idx = i;
        if(0 > pthread_create(&th[i], NULL, f, &args[i])) {
            perror("Error on thread create");
        }
    }

    for(i = 0; i < n; i++) {
        pthread_join(th[i], NULL);
    }

    for(i = 0; i < n; i++) {
        printf("%5d", arr[i]);
    }
    printf("\n");

    pthread_mutex_destroy(m);
    pthread_barrier_destroy(b);
    free(th);
    free(args);
    free(arr);
    free(m);
    free(b);
    return 0;
}