decrypt.py

"""
You have a bomb to defuse, and your time is running out! Your informer will provide you with a circular array code of length of n and a key k.
To decrypt the code, you must replace every number. All the numbers are replaced simultaneously.
If k > 0, replace the i^th number with the sum of the next k numbers.
If k < 0, replace the i^th number with the sum of the previous k numbers.
If k == 0, replace the i^th number with 0.
As code is circular, the next element of code[n-1] is code[0], and the previous element of code[0] is code[n-1].
Given the circular array code and an integer key k, return the decrypted code to defuse the bomb!

Example 1:
Input: code = [5,7,1,4], k = 3
Output: [12,10,16,13]
Explanation: Each number is replaced by the sum of the next 3 numbers. The decrypted code is [7+1+4, 1+4+5, 4+5+7, 5+7+1]. Notice that the numbers wrap around.

Example 2:
Input: code = [1,2,3,4], k = 0
Output: [0,0,0,0]
Explanation: When k is zero, the numbers are replaced by 0. 

Example 3:
Input: code = [2,4,9,3], k = -2
Output: [12,5,6,13]
Explanation: The decrypted code is [3+9, 2+3, 4+2, 9+4]. Notice that the numbers wrap around again. If k is negative, the sum is of the previous numbers.
 
Constraints:
n == code.length
1 <= n <= 100
1 <= code[i] <= 100
-(n - 1) <= k <= n - 1
"""
from typing import List

class Solution:
    def decrypt(self, code: List[int], k: int) -> List[int]:
        n = len(code)
        result = [0] * n
        if k == 0:
            return result
        
        for i in range(n):
            if k > 0:
                for j in range(1, k + 1):
                    result[i] += code[(i + j) % n]
            else:
                for j in range(1, abs(k) + 1):
                    result[i] += code[(i - j) % n]
        
        return result
        
# Test Cases
s = Solution()
print(s.decrypt([5,7,1,4], 3)) # [12,10,16,13]
print(s.decrypt([1,2,3,4], 0)) # [0,0,0,0]
print(s.decrypt([2,4,9,3], -2)) # [12,5,6,13]