Steps of counting sort in MPI: segmentation fault 11

Question

I have this code that implements the counting sort in C:

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

int main(){
    //create an array of N random elements
    int N = 100;
    int my_array[N];
    srand(time(NULL));
    int i;
    for (i=0; i<N; i++){
        my_array[i]=rand()%100 + 1;
    }
    //print the array 
    for (i=0; i<N; i++){
        printf("%d ", my_array[i]);
    } 

    clock_t start_time, end_time;
    double computation_time;
    start_time = clock();

    //define the minimum and the maximum as the first element of the array
    int min_array=my_array[0];
    int max_array=my_array[0];

    printf("\n--------------\n");

    //find the minimum and the maximum of the array
    for(i=0; i<N; i++){
        if(my_array[i]<min_array){
            min_array=my_array[i];
        }
        else if(my_array[i]>max_array){
            max_array=my_array[i];
        }
    }

    //check if it worked
    printf("max_array %d\n", max_array);
    printf("min_array %d\n", min_array);

    //
    int range_array;
    range_array = max_array - min_array + 1;
    int count_array[range_array];
    for(i=0; i<range_array;i++)
        count_array[i]=0;

    int j=0;
    
    for(int i=0; i<N; i++){
        count_array[my_array[i]-min_array]=count_array[my_array[i]-min_array]+1;
    }
    
    int z = 0;

    for(i=min_array; i<=max_array; i++){
        for(j=0; j<count_array[i-min_array];j++)
            my_array[z++]=i;
            //z=z+1;
    }

    end_time = clock();
    computation_time = ((double) (end_time - start_time)) / CLOCKS_PER_SEC;
    printf("Time Taken: %lf \n", computation_time);

    for(i=0; i<N; i++){
        printf("%d ", my_array[i]);
    }

    printf("\n--------------\n");
    printf("Time Taken: %lf \n", computation_time);

}

I have to implement this code using MPI. Basically, the first step of counting sort is to find the maximum and the minimum of an array. So I started trying to implement this search for max and min using MPI:

// First call MPI_Init
    MPI_Init(&argc, &argv);
    t1 = MPI_Wtime(); 
    // Get my rank
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
    // Get the number of ranks
    MPI_Comm_size(MPI_COMM_WORLD,&n_ranks);


    //define the minimum and the maximum as the first element of the array
    int min_array=my_array[0];
    int max_array=my_array[0];

    printf("\n--------------\n");

    MPI_Reduce(my_array,&min_array,N,MPI_INT,MPI_MIN,0,MPI_COMM_WORLD);
    MPI_Reduce(my_array,&max_array,N,MPI_INT,MPI_MAX,0,MPI_COMM_WORLD);

    if (rank == 0){
        printf("Max_value is: %d\n", max_array);
        printf("Min_value is: %d\n", min_array);
    }

Inside the main, just after the creation of the array, I have written these lines of code in order to do this task of min and max. However, if I try to execute sometimes it compiles (but the search is wrong) and sometimes appears Segmentation fault: 11