1652. Defuse the Bomb

public class Solution
{
    public int[] Decrypt(int[] code, int k)
    {
        int n = code.Length;
        int[] ans = new int[n];
        if (k == 0)
            return ans;

        int sum = 0;
        int start = k > 0 ? 1 : n + k; // the start of the next k numbers
        int end = k > 0 ? k : n - 1;   // the end of the next k numbers

        for (int i = start; i <= end; ++i)
            sum += code[i];

        for (int i = 0; i < n; ++i)
        {
            ans[i] = sum;
            sum -= code[start++ % n];
            sum += code[++end % n];
        }

        return ans;
    }
}