创建100个随机整数的列表，返回最大值

Question

Write a Python function that will take a the list of 100 random integers between 0 and 1000 and return the maximum value. (Note: there is a builtin function named max but pretend you cannot use it.)

Here's what I tried:

import random

list = []
for i in range(100):
    list.append(random.randint(0,1000))          

def max(list):
    #sort list from least to greatest
    answer = list.sort()
    #get last item in list (max value)
    list.pop()

    return max  

print (max(list))

As you can see, what I'm confused about is how to correctly use the sort and pop methods to return the max value within the max function. I'm currently getting:

ParseError: bad input on line 12

Which is this line:

list.pop()

Not sure how to correct this. Thanks.

Answer 1

1) Your indentation was off

2) You managed to overwrite 2 Python builtins in 4 lines of code ( max() and list() ))

3) my_list.sort() does not return a list. It operates in place sorting the list in-place. On the contrary, sorted(my_list) does return a list so you can either do my_list.sort() or my_list = sorted(my_list) .

4) Your return was just wrong.

See the code below:

a_list = []
for i in range(100):
    a_list.append(random.randint(0, 1000))

def my_max(my_list):
    return sorted(my_list)[-1]  # here, the list we passed gets sorted and its last item is retrieved (item with index -1)

print(my_max(a_list))

Other interesting answers (hats off to @Rob) that feature a bit of cockiness:

def my_max(my_list):
    return min(l, key:lambda i: 1/i)

or

def my_max(my_list):
    return min(l, key:lambda i: -i)

Answer 2

my_list.sort() sorts the list itself. If you want to store your sorted list in answer , you should use:

answer = sorted(my_list)

You can also use a list comprehension to generate your first list as follows:

>>> random
>>> 
>>> my_list = [random.randint(0, 1000) for i in range(100)]
>>> answer = sorted(my_list)
>>> answer.pop()
996  # This should be different each time

Now, your function can be:

def max(my_list):
    # sort list from least to greatest
    answer = sorted(my_list)
    # get last item in list (max value)
    max = answer.pop()

    return max

If you still want to use the same list, you can do:

my_list.sort()
max = my_list.pop()

Note that: I prefer to call the list my_list because list is a python keyword.

Answer 3

I usually try to avoid using names that are have a predefined function / built-in names, this helps to avoid problems quite often. Like this it should work.

import random

my_list = []
for i in range(100):
    my_list.append(random.randint(0,1000))          

def my_max(my_list):
    #sort list from least to greatest
    my_list.sort()
    #get last item in list (max value)
    my_max = my_list.pop()

    return my_max

print my_max(my_list)