Countdown to Liftoff

問題

Count down from start to 1, then add "Liftoff!". Each number becomes one text entry.

Implement countdown(start).

start: The number to start counting down from.

Return the countdown as a list of strings, ending with "Liftoff!".

0 ≤ start ≤ 1,000

例 1

入力：
start = 3

期待される出力：
expected = ["3", "2", "1", "Liftoff!"]

入力：
long long start = 3;

期待される出力：
std::vector<std::string> expected = {"3", "2", "1", "Liftoff!"};

入力：
long start = 3;

期待される出力：
string[] expected = new string[] {"3", "2", "1", "Liftoff!"};

"3", "2", "1", then "Liftoff!".

例 2

入力：
start = 0

期待される出力：
expected = ["Liftoff!"]

入力：
long long start = 0;

期待される出力：
std::vector<std::string> expected = {"Liftoff!"};

入力：
long start = 0;

期待される出力：
string[] expected = new string[] {"Liftoff!"};

There is nothing to count, so only "Liftoff!" remains.

まずは自分で考えてから、ヒントを 1 つずつ開いてみましょう。

ヒント 1

Build the list by stepping downward from the starting number until you reach 1.

ヒント 2

Generate each entry as text, then append the final farewell message at the end.

ヒント 3

Remember the smallest input can skip the numeric loop and still return only the farewell.

目安の計算量

O(start) time, O(start) extra space

この課題はCodeUtility用に調整されています。上記の説明と制約に従ってください。