Writing a recursive function to find how many elements in list are greater than 30-CodePudding

I want to write a recursive function named greater_than_30(list_nums) which finds how many numbers in the given list are greater than 30.

eg:

list1 = [10, 35, 30, 50]
output - 2

Here is the function I have writter:

def greater_than_30(list_nums):
    if len(list_nums) == 1:
        if list_nums[0] > 30:
            return 1
            
    else:
        if list_nums[0] > greater_than_30(list_nums[1:]):
            return list_nums[0] 
        else:
            return greater_than_30(list_nums[1:])


>>>a_list = [13, 21, 50, 34, 29, 33]
print(greater_than_30(a_list))
3 #output expected
50 #output gotten

CodePudding user response：

You're never actually counting it there. If you replace

if list_nums[0] > greater_than_30(list_nums[1:]):
    return list_nums[0]

with

if list_nums[0] > 30:
    return 1   greater_than_30(list_nums[1:])

it will work as expected.

CodePudding user response：

Even though I can't understand why you'd want to do this trivial operation recursively, here's a solution:

list1 = [13, 21, 50, 34, 29, 33]

def greater_than_30(lst):
    if len(lst) == 0:
        return 0
    return (1 if lst[0] > 30 else 0)   greater_than_30(lst[1:])

print(greater_than_30(list1))

Output:

CodePudding user response：

def grater_than_30(my_list, count=0):
    if len(my_list) == 0:
        return count
    if my_list[0] > 30:
        count  = 1
    count = grater_than_30(my_list[1:], count)
    return count


list1 = [13, 21, 50, 34, 29, 33]
grater_than_30(list1)