SO P&T - 5

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>
#include <sys/types.h>

#define MAXN 100005
#define THMAX 5
#define min(x, y) (x <= y ? x : y)

int arr[MAXN];
pthread_mutex_t mtx = PTHREAD_MUTEX_INITIALIZER;
int flag = 0;
int stack[THMAX], top;

typedef struct{
    int a, b, x, y, idx;
}merge_range;

void* merge(void* data){
    //pthread_mutex_lock(&mtx);
    merge_range *args = data;
    int l = args-> a, r = args->b, i = args->x, j = args->y;
    int val = args -> idx;
    //pthread_mutex_unlock(&mtx);
    //printf("%d %d to %d %d\n", l, r, i, j);
    int x = l, y = j;
    int k, ord[MAXN];
    for(k = l; l <= r && i <= j; k++){
        if(arr[l] <= arr[i]) ord[k] = arr[l++];
        else ord[k] = arr[i++];
    }
    while(l <= r) ord[k++] = arr[l++];
    while(i <= j) ord[k++] = arr[i++];
    for(; x <= y; x++) arr[x] = ord[x];
    pthread_mutex_lock(&mtx);
    stack[++top] = val;
    pthread_mutex_unlock(&mtx);
    return NULL;
}

void merge_sort(int n){
    int i, j, qtd = 0, aux;
    pthread_t thr[THMAX];
    merge_range tmp[THMAX];

    for(i = 0; i < THMAX; i++) stack[i] = i;
    top = THMAX - 1;

    for(i = 1; i <= n; i <<= 1){
        for(j = 0; j + i <= n; j += (i << 1)  ){
            while(top < 0);
            aux = stack[top];
            tmp[ aux ].a = j; tmp[ aux ].b = j + i - 1;
            tmp[ aux ].x = min(tmp[ aux ].b + 1, n - 1); tmp[aux].y = min(tmp[aux].x + i - 1, n - 1);
            tmp[aux].idx = stack[aux];
            pthread_create( &thr[ aux ], NULL, &merge, &tmp[aux]);
            pthread_join(thr[ stack[top--] ], NULL);
         }
         while(top != THMAX - 1);
    }
}

int main(){
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);

    int n;
    scanf("%d", &n);

    int i;
    for(i = 0; i < n; i++){
        scanf("%d", arr + i);
    }

    merge_sort(n);

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