URL : https://www.hackerrank.com/challenges/alphabet-rangoli/problem
You are given an integer, N. Your task is to print an alphabet rangoli of size N. (Rangoli is a form of Indian folk art based on creation of patterns.)
Different sizes of alphabet rangoli are shown below:
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#size 3
----c----
--c-b-c--
c-b-a-b-c
--c-b-c--
----c----
#size 5
--------e--------
------e-d-e------
----e-d-c-d-e----
--e-d-c-b-c-d-e--
e-d-c-b-a-b-c-d-e
--e-d-c-b-c-d-e--
----e-d-c-d-e----
------e-d-e------
--------e--------
#size 10
------------------j------------------
----------------j-i-j----------------
--------------j-i-h-i-j--------------
------------j-i-h-g-h-i-j------------
----------j-i-h-g-f-g-h-i-j----------
--------j-i-h-g-f-e-f-g-h-i-j--------
------j-i-h-g-f-e-d-e-f-g-h-i-j------
----j-i-h-g-f-e-d-c-d-e-f-g-h-i-j----
--j-i-h-g-f-e-d-c-b-c-d-e-f-g-h-i-j--
j-i-h-g-f-e-d-c-b-a-b-c-d-e-f-g-h-i-j
--j-i-h-g-f-e-d-c-b-c-d-e-f-g-h-i-j--
----j-i-h-g-f-e-d-c-d-e-f-g-h-i-j----
------j-i-h-g-f-e-d-e-f-g-h-i-j------
--------j-i-h-g-f-e-f-g-h-i-j--------
----------j-i-h-g-f-g-h-i-j----------
------------j-i-h-g-h-i-j------------
--------------j-i-h-i-j--------------
----------------j-i-j----------------
------------------j------------------
The center of the rangoli has the first alphabet letter a, and the boundary has the Nth alphabet letter (in alphabetical order).
- Input Format
- Only one line of input containing N, the size of the rangoli.
- Constraints
- 0 < N < 27
- Output Format
- Print the alphabet rangoli in the format explained above.
문제풀이
- 숫자 n이 주어지면 1 ~ n 까지의 알파벳을 위의 그림처럼 출력하는 함수를 작성
- 알파벳을 a~z까지 저장(1 ~ 26)
- 일단 range를역순으로 (n-1, -n, -1)의 순서를 주어 출력하고 (ex: n = 3이면 (2,1,0,-1,-2)이 출력) 알파벳을 인덱싱 및 join으로 묶음
- 이후 center 함수를 사용하여 가로(너비)만큼 구해주면됨.
- 참고로 가로구하는 공식은 세로 * 2 - 1 이고 세로는 n * 2 - 1 이다. 이를 풀어 쓰면 (n * 2 - 1) * 2 - 1이고 이룰 전개하면 4 * n - 3이 된다
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def print_rangoli(n):
alpha = 'abcdefghijklmnopqrstuvwxyz'
for i in range(n-1, -n, -1):
string = '-'.join(alpha[n-1:abs(i):-1] + alpha[abs(i):n])
print(string.center(4 * n - 3, '-'))
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print_rangoli(10)
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------------------j------------------
----------------j-i-j----------------
--------------j-i-h-i-j--------------
------------j-i-h-g-h-i-j------------
----------j-i-h-g-f-g-h-i-j----------
--------j-i-h-g-f-e-f-g-h-i-j--------
------j-i-h-g-f-e-d-e-f-g-h-i-j------
----j-i-h-g-f-e-d-c-d-e-f-g-h-i-j----
--j-i-h-g-f-e-d-c-b-c-d-e-f-g-h-i-j--
j-i-h-g-f-e-d-c-b-a-b-c-d-e-f-g-h-i-j
--j-i-h-g-f-e-d-c-b-c-d-e-f-g-h-i-j--
----j-i-h-g-f-e-d-c-d-e-f-g-h-i-j----
------j-i-h-g-f-e-d-e-f-g-h-i-j------
--------j-i-h-g-f-e-f-g-h-i-j--------
----------j-i-h-g-f-g-h-i-j----------
------------j-i-h-g-h-i-j------------
--------------j-i-h-i-j--------------
----------------j-i-j----------------
------------------j------------------