1652. Defuse the Bomb #

Problem #

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

Problem Summary #

You have a bomb to defuse, and time is running out! Your informer will give you a circular array code of length n and a key k. To obtain the correct password, you need to replace every number. All 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.

Since 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 the integer key k, return the decrypted result to defuse the bomb!

Solution Approach #

• Given a code array, replace each element according to the rules.
• This is an easy problem; simply iterate according to the problem description.

Code #

package leetcode

func decrypt(code []int, k int) []int {
	if k == 0 {
		for i := 0; i < len(code); i++ {
			code[i] = 0
		}
		return code
	}
	count, sum, res := k, 0, make([]int, len(code))
	if k > 0 {
		for i := 0; i < len(code); i++ {
			for j := i + 1; j < len(code); j++ {
				if count == 0 {
					break
				}
				sum += code[j]
				count--
			}
			if count > 0 {
				for j := 0; j < len(code); j++ {
					if count == 0 {
						break
					}
					sum += code[j]
					count--
				}
			}
			res[i] = sum
			sum, count = 0, k
		}
	}
	if k < 0 {
		for i := 0; i < len(code); i++ {
			for j := i - 1; j >= 0; j-- {
				if count == 0 {
					break
				}
				sum += code[j]
				count++
			}
			if count < 0 {
				for j := len(code) - 1; j >= 0; j-- {
					if count == 0 {
						break
					}
					sum += code[j]
					count++
				}
			}
			res[i] = sum
			sum, count = 0, k
		}
	}
	return res
}