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 ith number with the sum of the next k numbers.
If k < 0, replace the ith number with the sum of the previous k numbers.
If k == 0, replace the ith number with 0.
As code is circular, the next element of code[n1] is code[0], and the previous element of code[0] is code[n1].
Given the circular array code and an integer key k, return the decrypted code to defuse the bomb!
Example 1:

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.
Solution
This is an easy challenge, we only need to iterate the array and calculate the previous(or latter) ksum
.
Note for the negative index, we need to add code.size()
and then mod
it into range [0, code.size()1]
.
Time complexity is O(N*k)

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