Replace First

Quiz>

In a given list the first element should become the last one.

An empty list or list with only one element should stay the same.

 

example

 

Input: 

List.

 

Output: 

Iterable.

 

Example:

replace_first([1, 2, 3, 4]) == [2, 3, 4, 1]
replace_first([1]) == [1]

 

from typing import Iterable


def replace_first(items: list) -> Iterable:
    # your code here
    return items


if __name__ == '__main__':
    print("Example:")
    print(list(replace_first([1, 2, 3, 4])))

    # These "asserts" are used for self-checking and not for an auto-testing
    assert list(replace_first([1, 2, 3, 4])) == [2, 3, 4, 1]
    assert list(replace_first([1])) == [1]
    assert list(replace_first([])) == []
    print("Coding complete? Click 'Check' to earn cool rewards!")

 

Solve>

1. items 리스트의 길이가 0 이상이면

def replace_first(items: list) -> Iterable:
    if len(items) > 0:

 

2. 첫 번째 원소를 가져올 리스트 생성

def replace_first(items: list) -> Iterable:
    if len(items) > 0:
        first_list = []

 

3. 첫 번째 원소를 for 문을 사용하여 가져옴

def replace_first(items: list) -> Iterable:
    if len(items) > 0:
        first_list = []

		for i in items[:1]:
            first_list.append(i)

 

4. 리스트의 2번째 원소부터 가져와서 맨 앞 원소가 뒤로 가야되므로 더하기로 구성

def replace_first(items: list) -> Iterable:
    if len(items) > 0:
        first_list = []
        
        for i in items[:1]:
            first_list.append(i)
            
        return items[1:] + first_list

 

5. 빈 리스트일 경우 items를 그대로 반환

def replace_first(items: list) -> Iterable:
    else:
        return items

 

Code>

def replace_first(items: list) -> Iterable:
    if len(items) > 0:
        first_list = []
        
        for i in items[:1]:
            first_list.append(i)
            
        return items[1:] + first_list
        
    else:
        return items

 

Example>

if __name__ == '__main__':
    print("Example:")
    print(list(replace_first([1, 2, 3, 4])))

    # These "asserts" are used for self-checking and not for an auto-testing
    assert list(replace_first([1, 2, 3, 4])) == [2, 3, 4, 1]
    assert list(replace_first([1])) == [1]
    assert list(replace_first([])) == []
    print("Coding complete? Click 'Check' to earn cool rewards!")

 

Result>

Example:

[2, 3, 4, 1]

Coding complete? Click 'Check' to earn cool rewards!