1652. Defuse the Bomb

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1652. Defuse the Bomb

Description

You have a bomb to defuse, and your time is running out! Your informer will provide you with a circular array codeof length of nand 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:

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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:

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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:

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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

Hints/Notes

Solution

Language: C++

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class Solution {
public:
    vector<int> decrypt(vector<int>& code, int k) {
        int n = code.size();
        vector<int> res(n, 0);
        if (!k) {
            return res;
        }
        int sum = 0;
        int start = k > 0 ? 1 : n + k, end = k > 0 ? k : n - 1;
        for (int i = start; i <= end; i++) {
            sum += code[i];
        }
        for (int i = 0; i < n; i++) {
            res[i] = sum;
            sum -= code[(start++) % n];
            sum += code[(++end) % n];
        }
        return res;
    }
};