如何将用户输入的数值归纳成数组？

问题简单来说就是 提示用户输入数字，一旦不是数字则显示invalid input，但程序还会继续让用户输入，直到用户输入'done'。之后会显示用户输入的最大值和最小值。但是感觉不知道怎么下手啊，下面是我的代码

largest = None
smallest = None
while True:
    num = input("Enter a number: ")
    if num == "done" :
        break
    try:
            num = float(num)
    except:
        print("Invalid input")
        continue
for largest in num:
    if largest is None:
        largest = num
    elif num > largest:
        largest = num
print("Maximum is ", largest)
for smallest in num:
        if smallest is None:
                smallest = num
           elif num < smallest:
            smallest = num
print("Minimum is ", smallest)

num_list = []
while True:
    num = input("Enter a number: ")
    if num == "done" :
        break
    try:
        num_list.append(float(num))
    except:
        print("Invalid input")
print("Maximum is ", max(num_list))
print("Minimum is ", min(num_list))