right = 100
left = 1
def my_test():
    my_list = []
    def my_left():
        global left
        global right
        while left < right:
            my_list.append(left)
            left += 1
    def my_right():
        global right
        global left
        while left < right:
            print(2) # 删除这行返回5049------------------------------------问题不删除这行5050
            my_list.append(right)
            right -= 1
    t1 = threading.Thread(target=my_left)
    t2 = threading.Thread(target=my_right)
    t2.start()
    t1.start()
    time.sleep(1)
    print('len:', len(my_list),'sum:', sum(my_list), my_list)

my_test()