LeetCode in Kotlin

1652. Defuse the Bomb

Easy

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[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

Solution

class Solution {
    fun decrypt(code: IntArray, k: Int): IntArray {
        val result = IntArray(code.size)
        val len = code.size
        if (k == 0) {
            for (i in code.indices) {
                result[i] = 0
            }
        } else if (k > 0) {
            var kSum = 0
            for (i in 1..k) {
                kSum += code[i]
            }
            result[0] = kSum
            for (i in 1 until len) {
                kSum -= code[i]
                kSum += code[(i + k) % len]
                result[i] = kSum
            }
        } else {
            var kSum = 0
            val kVal = Math.abs(k)
            for (i in len - 1 downTo len - kVal) {
                kSum += code[i]
            }
            result[0] = kSum
            for (i in 1 until len) {
                kSum -= code[(len - kVal + i - 1) % len]
                kSum += code[i - 1]
                result[i] = kSum
            }
        }
        return result
    }
}

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