判断将素数判断函数primenumber的循环范围从range(2,number)改为range(2,number//2)是否能降低时间复杂度

def primenumber(number):
    if number < 2:
        print(number, "不是素数！")
    else: 
        for i in range(2, number):
            if number % i == 0:
                print(number, "不是素数！")
                break
        else:
            print(number, "是素数!")