[Hackerrank] Lists
문제 설명
Consider a list (list = []). You can perform the following commands:
insert i e: Insert integer e at position i.
print: Print the list.
remove e: Delete the first occurrence of integer e.
append e: Insert integer e at the end of the list.
sort: Sort the list.
pop: Pop the last element from the list.
reverse: Reverse the list.
Initialize your list and read in the value of n followed by n lines of commands where each command will be of the 7 types listed above. Iterate through each command in order and perform the corresponding operation on your list.
stack이라는 자료구조를 직접 구현해보는 문제처럼,
list라는 자료구조를 한번 구현해보라는 문제인것같다!!
제한사항
Input Format
The first line contains an integer, n, denoting the number of commands. Each line i of the n subsequent lines contains one of the commands described above.
Output Format
For each command of type print, print the list on a new line.
Others
- The elements added to the list must be integers.
입출력 예
Sample Input 0
12
insert 0 5
insert 1 10
insert 0 6
print
remove 6
append 9
append 1
sort
print
pop
reverse
print
Sample Output 0
[6, 5, 10]
[1, 5, 9, 10]
[9, 5, 1]
Idea
class 정의하고 무작정 해보자!!
Code
class List:
def __init__(self):
self.arr = list()
def insert(self, position, value):
self.arr.insert(position, value)
def append(self, value):
self.arr.append(value)
def print(self):
print(self.arr)
def remove(self, value):
if value not in self.arr:
print(f"It doesn't exist in the list.---->[{value}]")
return -1
self.arr.remove(value)
def sort(self):
self.arr.sort()
def pop(self):
if len(self.arr) == 0:
print("Empty")
return -1
self.arr.pop()
def reverse(self):
if len(self.arr) == 0:
print("Empty")
return -1
self.arr = self.arr[::-1]
if __name__ == '__main__':
arr = List()
for i in range(int(input())):
query = input()
if query == "print":
arr.print()
elif query == "pop":
arr.pop()
elif query == "reverse":
arr.reverse()
elif query == "sort":
arr.sort()
elif query.startswith("insert"):
query, position, value = query.split()
arr.insert(int(position), int(value))
elif query.startswith("append"):
query, value = query.split()
arr.append(int(value))
elif query.startswith("remove"):
query, value = query.split()
arr.remove(int(value))
Explain
어려운건 하나도 없지만, 흥미로운점을 발견했다.
hackerrank의 code edit는 ascii character만 작성해서 제출할수있다.
error 출력을 한글로 할려고 했더니, 제출이 불가했다.
저의 코드를 보시는것보다, 밑에 코드를 보는게 더 흥미로울것같습니다!!
다른사람의 풀이 #1
if __name__ == '__main__':
L = []
for _ in range(0, int(raw_input())):
user_input = raw_input().split(' ')
command = user_input.pop(0)
if len(user_input) > 0:
if 'insert' == command:
eval("L.{0}({1}, {2})".format(command, user_input[0], user_input[1]))
else:
eval("L.{0}({1})".format(command, user_input[0]))
elif command == 'print':
print L
else:
eval("L.{0}()".format(command))
이 코드는 eval()이라는 함수를 사용했다.
eval is evil
이라는 말이있는데, 확실히 위험하긴하다!!
x = input()
print eval(x)
위와 같은 코드가 있을때…
__import__('os').system('rm -rf *')
폭탄이 터졌다 ㅋㅋㅋ
다른사람의 풀이 #2
if __name__ == '__main__':
import builtins
N = int(input())
list_ = list()
for _ in range(N):
func_ = str(input()).split()
getattr(builtins,'print')(list_) if func_[0] == 'print' else getattr(list_,func_[0])(*map(int,func_[1:]))
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