long long total_times_in_cycle;
long long local_number_toss;
pthread_mutex_t times_in_cycle_mutex = PTHREAD_MUTEX_INITIALIZER;
void* do_Monte_Carlo_simulation(void* my_rank){
	double offset = RAND_MAX / (double)2;
    long long times_in_cycle = 0;
    long long i;
    for(i = 0; i < local_number_toss; ++i){
        double x = rand() / offset - 1;
        double y = rand() / offset - 1;
        if(x*x + y*y < 1){
            times_in_cycle++;
        }
    }
    pthread_mutex_lock(&times_in_cycle_mutex);
    total_times_in_cycle += times_in_cycle;
    pthread_mutex_unlock(&times_in_cycle_mutex);
}

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

int generate_rand_count;
int thread_count;

// 被線程執(zhí)行的函數(shù)
void* thread_func(void* my_rank){
    int i;
    int local_rand_count = generate_rand_count / thread_count;
    for(i = 0; i < local_rand_count; ++i){
        printf("%d ", rand());
    }
}

int main(int argc, char* argv[]){
    pthread_t* all_threads_id;

    // 從命令行獲取要生成的隨機(jī)數(shù)的數(shù)量以及這些隨機(jī)數(shù)由多少個(gè)線程來生成
    generate_rand_count = strtol(argv[1], NULL, 10);
    thread_count = strtol(argv[2], NULL, 10);
    all_threads_id = malloc(sizeof(pthread_t) * thread_count);

    // 設(shè)置隨機(jī)數(shù)種子
    srand(0);

    // 創(chuàng)建線程
    int i;
    for(i = 0; i < thread_count; ++i){
        pthread_create(&all_threads_id[i], NULL, thread_func, (void*) i);
    }

    for(i = 0; i < thread_count; ++i){
        pthread_join(all_threads_id[i], NULL);
    }
    
    printf("\n");
    free(all_threads_id);
    return 0;
}

int rand_r(unsigned int *seedp);

long long total_times_in_cycle;
long long local_number_toss;
pthread_mutex_t times_in_cycle_mutex = PTHREAD_MUTEX_INITIALIZER;
void* do_Monte_Carlo_simulation(void* my_rank){
	unsigned int local_seed = time(NULL);
	double offset = RAND_MAX / (double)2;
    long long times_in_cycle = 0;
    long long i;
    for(i = 0; i < local_number_toss; ++i){
        double x = rand_r(&local_seed) / offset - 1;
        double y = rand_r(&local_seed) / offset - 1;
        if(x*x + y*y < 1){
            times_in_cycle++;
        }
    }
    pthread_mutex_lock(&times_in_cycle_mutex);
    total_times_in_cycle += times_in_cycle;
    pthread_mutex_unlock(&times_in_cycle_mutex);
}