In normal circumstances, the following 4 questions are pretty manageable and doable I guess. But their difficulty steps up when we are required to write them using ONE line of code. I'm guessing not many of you will be able to solve all 4 questions using ONE line of code, but I want you to prove me wrong.

Disclaimer — I've personally solved all 4 questions in one line, and they are doable. It's just not easy.

1) Sorting Fruits By Count

fruits = ["apple", "apple", "orange", "pear", "apple", "orange"]

You are given a list of fruits, and some fruits appear multiple times. Write a function sort_count(fruits) that takes in this list, counts the number of times each fruit appears, and sorts them by this condition.

sort_count(fruits)   # ["pear", "orange" ,"apple"]

Here, pear appears once, orange appears twice and apple appears thrice, and that is why we get ["pear", "orange", "apple"]. Write this function using ONE line of code.

2) Replacing None Values With Average

lis = [1, 2, None, 3, 5, None, 4]

You are given a list of numbers with some None values. Write a function replace_none(lis) that takes in this list, and returns a new version of this list where None are replaced with the average of the other numbers.

replace_none(lis)   # [1, 2, 3, 3, 5, 3, 4]

Here, the average of the numbers is 3 as (1+2+3+5+4)/5 == 3. We then replace all None values with 3. Write this function using ONE line of code.

3) Counting Holes On A Bridge

bridge = [1,0,1,1,0,0,0,1,0,0,1,1]

You are given a list containing only 1's and 0's. This list represents a bridge, 1's represent wood, and 0's represent holes. 2 holes (0's) that are right next to each other make up a larger hole.

Write a function count_holes(bridge) that counts the number of holes (regardless of how big or small the hole it) on the bridge.

count_holes(bridge)   # 3

In this bridge, there are 3 holes — remember that multiple 0's directly next to one another make up a hole.

4) Extracting Keys From Messy Nested Dictionary

data = {
    "type": "video",
    "videoID": "vid001",
    "links": [
        {"type":"video", "videoID":"vid002", "links":[]},
        {   "type":"video", 
            "videoID":"vid003",
            "links": [
            {"type": "video", "videoID":"vid004"},
            {"type": "video", "videoID":"vid005"},
            ]
        },
        {"type":"video", "videoID":"vid006"},
        {   "type":"video",
            "videoID":"vid007",
            "links": [
            {"type":"video", "videoID":"vid008", "links": [
                {   "type":"video", 
                    "videoID":"vid009",
                    "links": [{"type":"video", "videoID":"vid010"}]
                }
            ]}
        ]},
    ]
}

You are given a messy dictionary with multiple levels of nesting (dictionaries & lists). Write a function extract(data, key) that takes in 1) this messy nested dictionary and 2) a string key, and returns a list containing all values with the key.

extract(data, "videoID")
# ['vid001', 'vid002', 'vid003', 'vid004', 'vid005', 'vid006', 'vid007', 'vid008', 'vid009', 'vid010']

Remember to write this function using ONE line of code! HINT — recursion is needed to write this function in one line.

Conclusion

Did you manage to solve them all and prove me wrong?

Some Final words

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